A gang was a group of associated individuals.
The Tenth Doctor briefly considered using the term to collectively address Rose Tyler and Mickey Smith. (TV: School Reunion)
The Thirteenth Doctor sometimes called her group of friends "gang", (TV: The Woman Who Fell to Earth, Rosa, COMIC: A New Beginning, Kerblam!, The Witchfinders, Resolution) as well as "fam" (TV: The Woman Who Fell to Earth, Arachnids in the UK, The Witchfinders, The Battle of Ranskoor Av Kolos, Resolution) and "Team TARDIS". (TV: Arachnids in the UK)
Jack Chance was the leader of Sabalom Glitz's gang of robbers. (PROSE: Mission: Impractical)
The Seventh Doctor was caught in a gang war's crossfire in San Francisco on 30 December 1999. This lead to him regenerating into his eighth incarnation. (TV: Doctor Who)
Baz Bailey was the leader of a gang at Coal Hill School that dealt in illicit drugs. (PROSE: The Eight Doctors)
Sunset Strip, a market visited frequently by criminal gang members, was most busy on Tuesdays. (COMIC: Gangster's Paradise)