Girls gathering there's drink! (4)
I believe the answer is:
bevy
I believe this clue is a triple definition!
'girls' is the first definition.
(I have seen 'many girls' mean 'bevy' so perhaps 'girls' could also mean 'bevy')
'gathering' is the second definition.
(bevy is a kind of gathering)
'there's' acts as a link.
'drink' is the third definition.
(short for beverage)
(Other definitions for bevy that I've seen before include "Group of e.g. girls" , "Group of birds or girls" , "Pack" , "Flock; alcoholic drink" , "Assemblage" .)