Words collapsed before weapon (5)
I believe the answer is:
sword
'weapon' is the definition.
(I know that sword is a type of weapon)
'words collapsed' is the wordplay.
'collapsed' indicates anagramming the letters.
'words' with letters rearranged gives 'SWORD'.
'before' acts as a link.
(Other definitions for sword that I've seen before include "Sharp weapon" , "Normandy beach" , "Combat" , "Weapon of steel" , "Sharp-edged weapon" .)