Cutting instrument (8)
I believe the answer is:
scissors
'cutting instrument' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for scissors that I've seen before include "Cross sis with two-bladed implement" , "Tool with two crossed blades" , "Equipment for dealing with locks" , "Wrestling hold" , "Cutting instrument made of two joined blades with handles" .)