Drink not right for social gathering (3)
I believe the answer is:
bee
'social gathering' is the definition.
(bee is a kind of social gathering)
'drink not right for' is the wordplay.
'drink' becomes 'beer' (beer is a kind of drink).
'not' suggests deleting specific letters.
'right for' becomes 'r' (I've seen this in other clues).
'beer' with 'r' taken out is 'BEE'.
(Other definitions for bee that I've seen before include "Honey generator" , "Busy person" , "Insect, may be in bonnet" , "Honey-making insect" , "competition" .)