Enjoyment in pool curtailed (3)
I believe the answer is:
fun
'enjoyment' is the definition.
(enjoyable activities)
'pool curtailed' is the wordplay.
'pool' becomes 'fund' (I've seen this before).
'curtailed' means to remove the last letter.
'fund' with its final letter removed is 'FUN'.
'in' acts as a link.
(Other definitions for fun that I've seen before include "Light-hearted amusement, jollity" , "entertainment" , "Enjoyment" , "'Merriment, playfulness (3)'" , "Playful amusement" .)