Game for a drink (6)
I believe the answer is:
squash
I believe this is a double definition.
'game' is the first definition.
(squash is a kind of game)
'for a drink' is the second definition.
(I've seen this before)
(Other definitions for squash that I've seen before include "Crush or squeeze flat" , "behind glass" , "juice that's been watered down" , "Ballgame for two" , "Court game - marrow-like plant" .)