Rifle attachment (7)
I believe the answer is:
bayonet
'rifle attachment' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for bayonet that I've seen before include "Knife fixed to the end of a rifle" , "Pointed weapon" , "Dagger attached to 26 Across" , "Type of light bulb fitting" , "Lethal Weapon" .)