Comrade's drink knocked over (3)
I believe the answer is:
pal
'comrade's' is the definition.
(I've seen this in other clues)
'drink knocked over' is the wordplay.
'drink' becomes 'lap' (lapping is a kind of drinking).
'knocked over' shows that the letters should be reversed in order.
'lap' written backwards gives 'PAL'.
(Other definitions for pal that I've seen before include "Bud" , "Crony" , "Buddy, chum" , "Mate, informal friend" , "Close friend" .)