Lift up belly in pool (7)
I believe the answer is:
jackpot
'pool' is the definition.
(pool of winnings or prize money)
'lift up belly' is the wordplay.
'lift up' becomes 'jack' (jacking is a kind of lifting. I am not sure about the 'up' bit.).
'belly' becomes 'pot' (synonyms).
'jack'+'pot'='JACKPOT'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for jackpot that I've seen before include "Large cash prize" , "best prize!" , "pool" , "The big pay-out - hit it" , "First prize" .)