Corporation Yank backs (3)
I believe the answer is:
gut
'corporation' is the definition.
(both can humorously mean belly fat)
'yank backs' is the wordplay.
'yank' becomes 'tug' (both can mean to pull sharply).
'backs' shows that the letters should be reversed in order.
'tug' reversed gives 'GUT'.
(Other definitions for gut that I've seen before include "Part of the alimentary canal" , "Cologne's good" , "Empty" , "Eviscerate" , "The stuff of a violin string" .)