Potter actor underwater? (4,6)

'potter' is the definition.
(a pool player pots balls)

'actor underwater?' is the wordplay.
I cannot really see how this works, but
'actor' could be 'player' (synonyms) and 'player' is found in the answer.
The remaining letters 'pool' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).