Repair damaged fencing sword (6)
I believe the answer is:
rapier
'fencing sword' is the definition.
(I've seen this before)
'repair damaged' is the wordplay.
'damaged' indicates anagramming the letters.
'repair' with letters rearranged gives 'RAPIER'.
(Other definitions for rapier that I've seen before include "fencing equipment" , "Fine-bladed sword" , "Thrusting weapon" , "A thin double-edged sword" , "Thin sharp sword" .)