Repair broken weapon (6)
I believe the answer is:
rapier
'weapon' is the definition.
(rapier is a kind of weapon)
'repair broken' is the wordplay.
'broken' is an anagram indicator.
'repair' with letters rearranged gives 'RAPIER'.
(Other definitions for rapier that I've seen before include "Light sword" , "Thrusting weapon" , "fencing equipment" , "Narrow sword with two-edged blade" , "Long slender sword" .)