Boxer's big tummy? (12)
I believe the answer is:
middleweight
This clue could be a double definition.
'boxer's' is the first definition.
(middleweight is a kind of boxer)
'big tummy?' is the second definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
Can you help me to learn more?
(Other definitions for middleweight that I've seen before include "Boxing category" , "Boxer" .)