Strike overwhelming a corporation (6)
I believe the answer is:
paunch
'corporation' is the definition.
(synonyms)
'strike overwhelming a' is the wordplay.
'strike' becomes 'punch' (I've seen this before).
'overwhelming' is an insertion indicator.
'punch' placed around 'a' is 'PAUNCH'.
(Other definitions for paunch that I've seen before include "Protruding belly" , "Beer-belly" , "Gut" , "Beer belly" , "Pot" .)