Bad, bad sign for corporation (7)
I believe the answer is:
abdomen
'corporation' is the definition.
(I've seen this before)
'bad bad sign' is the wordplay.
'bad' is an anagram indicator.
'sign' becomes 'omen' (omen is a kind of sign).
'bad' with letters rearranged gives 'abd'.
'abd'+'omen'='ABDOMEN'
'for' is the link.
(Other definitions for abdomen that I've seen before include "Bodily region" , "Insect's body part" , "4 part of insect" , "Mean bod (anag.)" , "Ban demo (anag)" .)