Hit one in the belly (6)
I believe the answer is:
paunch
'the belly' is the definition.
(synonyms)
'hit one' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'un' (northern English dialect form of 'one') and 'un' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'in' is the link.
Can you help me to learn more?
(Other definitions for paunch that I've seen before include "Large stomach or belly" , "corporation" , "Gut" , "Protruding belly" , "Beer belly" .)