Pears used as a weapon (5)
I believe the answer is:
spear
'a weapon' is the definition.
(I know that spear is a type of weapon)
'pears used' is the wordplay.
'used' is an anagram indicator.
'pears' anagrammed gives 'SPEAR'.
'as' acts as a link.
(Other definitions for spear that I've seen before include "Stabbing, throwing, weapon" , "asparagus for example" , "Sharp weapon" , "stick" , "Impale" .)