Hammer or chisel (4)
I believe the answer is:
tool
This clue is a double definition.
'hammer' is the first definition.
(I've seen this in another clue)
'chisel' is the second definition.
(thesaurus)
(Other definitions for tool that I've seen before include "Weapon" , "Practical implement" , "Device used for work" , "Cat's-paw; impress design on" , "For example, saw" .)