Part of corporation needing to remodel bad sign (7)
I believe the answer is:
abdomen
'part of corporation' is the definition.
(corporation can humorously mean belly fat)
'to remodel bad sign' is the wordplay.
'to remodel' is an anagram indicator.
'sign' becomes 'omen' (omen is a kind of sign).
'bad' anagrammed gives 'abd'.
'abd'+'omen'='ABDOMEN'
'needing' acts as a link.
(Other definitions for abdomen that I've seen before include "Midriff" , "Where one digests" , "4 part of insect" , "Site of corporation" , "guts" .)