Former X factor judge and N-Dubz star Tulisa told an undercover reporter she could get hold of "white sweets" in an apparent reference to cocaine, a court heard.
The singer "did not negotiate the price or amount" but "did all she could to make a supply of cocaine happen," prosecutor Tim Cray said.
He added Tulisa's role in the deal at London's Dorchester Hotel in May last year was "instrumental."
The trial at Southwark Crown Court continues.
N-Dubz rapper Dappy, who was found guilty of assault and affray, has lost a challenge against his conviction at the Court of Appeal in London.
Dino Contostavlos, better known as Dappy from N-Dubz, who was found guilty of assault and affray, will have a conviction challenge heard by leading judges today.
The Lord Chief Justice Lord Judge, sitting with two other judges at the Court of Appeal in London, is to hear his case.
The 25-year-old singer was convicted in January in connection with a brawl at a petrol station in Guildford, Surrey.
In February, the pop star was sentenced at Guildford Crown Court and given a six-month sentence, suspended for 18 months.
He was also ordered to carry out 150 hours community service.
The jury in the trial of N-Dubz rapper Dappy, who is accused with two friends of affray in connection with a petrol station brawl, has retired to consider its verdict.
The 25-year-old singer, whose real name is Costadinos Contostavlos, is on trial alongside Kieran Vassell, 25, of Hammersmith, west London, and Kalonji Stewart, 32, of Harborne, Birmingham, who both face a single charge of affray.
The case relates to a fight which broke out at a Guildford petrol station in the early hours of February 28 last year, leaving three men with facial injuries.
N-Dubz rapper Dappy has denied sparking a petrol station brawl because he was "disrespected" by two teenage women who called him "boring".
The 25-year-old is charged with affray, two counts of common assault and one of assault by beating in connection with the fight at the Shell garage in Woodbridge Road, Guildford, Surrey, at about 3.30am on February 28 last year.
The trial at Guildford Crown Court has heard that Dappy had been out that night celebrating at a nightclub the release of his new single Rockstar featuring Queen guitarist Brian May.
The case continues.
N-Dubz rapper Dappy sparked a "mob attack" at a petrol station when he spat at two girls who refused to get into a car with him and two friends, a court has heard.
Prosecutors said the 25-year-old singer spat at and insulted the girls after they turned down the invite at a Shell garage in Guildford, Surrey, in the early hours of February 28 last year, before spitting at another man, David Jenkins, who had defended them.
Prosecuting barrister Brian Stork told the jury at Guildford Crown Court that Dappy swung a punch at Mr Jenkins, which launched the "mob-handed, utterly unlawful and aggressive attack."
Two other men, Kieran Vassell and Alfred Miller, who had arrived in a second Mercedes car with other unidentified men, joined the attack, he said. Mr Stork showed the jury brief CCTV footage from the garage of the brawl.
Dappy, who is charged under his real name of Costadinos Contostavlos, denies two counts of common assault on the two women, one of assault by beating, of Mr Jenkins, and one of affray. The trial continues.
N-Dubz rapper Dappy has left Guildford Crown Court after the trail began over an alleged fight at a petrol station in Surrey which left three men with serious facial injuries.
The rapper, appearing under his real name of Dino Costas Contostavlos, is being tried alongside three co-defendants at Guildford Crown Court.
N-Dubz rapper Dappy is standing trial today following a fight at a petrol station which left three men with serious facial injuries. He was arrested in March last year following an incident at a Shell garage in Guildford, Surrey.
Dappy is being tried alongside three co-defendants at Guildford Crown Court. He was charged with affray.
N-Dubz rapper Dappy has been charged with affray after a fight at a petrol station left three men with serious facial injuries.
The singer was arrested on March 12 following the incident on the forecourt of a Shell garage in Woodbridge Road, Guildford, in the early hours of February 28.
Dappy and a 27-year-old man allegedly approached two girls and three men and asked the girls to go with them.
When they refused, one of the rejected men allegedly spat at one of the girls.
A fight then allegedly broke out between Dappy and his friend and another group of up to six men.
Surrey Police said the singer was charged under the name Dino Costas Contostavlos at a police station last night.
Three other men have also been charged with affray in relation to the incident.
All four have been bailed to appear before Guildford Magistrates' Court on Thursday, May 24.