Search and rob to get gun (5)
I believe the answer is:
rifle
I believe this is a double definition.
'search and rob' is the first definition.
(I've seen this in another clue)
'gun' is the second definition.
(I know that Rifle is a type of small-arm)
'to get' acts as a link.
(Other definitions for rifle that I've seen before include "Shoulder firearm" , "Search and rob for army weapon" , "Sack; firearm" , "loot in sack" , "Ransack; a weapon" .)