Revolver, for instance (3)
I believe the answer is:
gun
'revolver for instance' is the definition.
(I know that revolver is a type of pistol)
This is the entire clue.
(Other definitions for gun that I've seen before include "Arm" , "Throttle" , "What has barrel" , "It can be carried by 15 Ac" , "Firearm" .)