Submachine gun (3)
I believe the answer is:
uzi
'submachine gun' is the definition.
(I know that Uzi is a type of submachine gun)
This is all the clue.
(Other definitions for uzi that I've seen before include "Submachine-gun" , "Type of submachine gun" , "kind of weapon" , "Israeli sub-machine gun" , "killer" .)