Guy's wife (3)
I believe the answer is:
rib
I believe this is a double definition.
'guy's' is the first definition.
(I've seen this before)
'wife' is the second definition.
(thesaurus)
(Other definitions for rib that I've seen before include "Thin bone" , "Guy" , "Tease (sl.)" , "structural member" , "Part of vault" .)