Came to fix old weapon (4)
I believe the answer is:
mace
'old weapon' is the definition.
(I've seen this in another clue)
'came to fix' is the wordplay.
'to fix' indicates anagramming the letters (I've seen 'fixed' mean this).
'came' anagrammed gives 'MACE'.
(Other definitions for mace that I've seen before include "Came to get nutmeg spice" , "Ceremonial staff or kind of spice" , "put on the rack?" , "Spice; heavy club" , "Came to find ceremonial staff" .)