Pears used as a weapon (5)
I believe the answer is:
Here is my best explanation:
'a weapon' is the definition.
(spear is a kind of weapon)
'pears used' is the subsidiary indication.
'used' is an anagram indicator.
'pears' anagrammed gives 'spear'.
'as' is the link.
(Other definitions for spear that I've seen before include "Long pointed weapon", "Weapon for throwing", "Shafted weapon for throwing or thrusting", "Pointed weapon", "Sharp weapon", "Old weapon", "Throwing weapon", "Weapon; asparagus stem", "Sharp-tipped weapon" and "Stabbing, throwing, weapon".)