Water polo, possibly, or other game (4)
I believe the answer is:
pool
'water' is the definition.
(pool is a kind of water)
'polo possibly or other game' is the wordplay.
'polo' can be anagrammed to 'POOL'.
However, I'm not sure how the anagram is indicated.
Can you help me to learn more?
(Other definitions for pool that I've seen before include "Small body of still water" , "Organization of people or resources that can be shared" , "Kitty; a billiard game" , "Bathing place" , "Small lake" .)