Search for a weapon (5)
I believe the answer is:
rifle
This clue is a double definition.
'search' is the first definition.
(as in rifling around for something)
'weapon' is the second definition.
(rifle is a kind of weapon)
'for a' acts as a link.
(Other definitions for rifle that I've seen before include "Strip - firearm" , "An arm" , "Search and rob for army weapon" , "Security provider with stock" , "Gun; plunder" .)