Game of polo? (4)
I believe the answer is:
pool
'game' is the definition.
(I know that pool is a type of table game)
'of polo?' is the wordplay.
'of' indicates anagramming the letters (the answer comes from or 'of' the letters).
'polo' anagrammed gives 'POOL'.
(Other definitions for pool that I've seen before include "Small body of still water" , "stakes" , "Shared supply; game" , "share" , "Puddle - game with balls" .)