Words used as weapon (5)
I believe the answer is:
sword
'weapon' is the definition.
(sword is a kind of weapon)
'words used' is the wordplay.
'used' indicates an anagram.
'words' with letters rearranged gives 'SWORD'.
'as' acts as a link.
(Other definitions for sword that I've seen before include "Two-edged weapon" , "Cutting weapon" , "Normandy beach" , "Bladed weapon" , "Sharp-edged weapon" .)