Carbon copy for head (4)
I believe the answer is:
cape
'head' is the definition.
(thesaurus)
'carbon copy' is the wordplay.
'carbon' becomes 'c' (C is the chemical symbol for carbon).
'copy' becomes 'ape' ('ape' can be a synonym of 'copy').
'c'+'ape'='CAPE'
'for' is the link.
(Other definitions for cape that I've seen before include "Covering for the shoulders" , "Shoulders? They're covered in it" , "Wrath perhaps" , "Florida space flight centre" , "Wrath, say" .)