Weapon in bad repair (6)
I believe the answer is:
rapier
'weapon' is the definition.
(rapier is a kind of weapon)
'bad repair' is the wordplay.
'bad' indicates anagramming the letters.
'repair' anagrammed gives 'RAPIER'.
'in' is the link.
(Other definitions for rapier that I've seen before include "Thrusting weapon" , "A thin double-edged sword" , "A fencing sword for repair" , "Light sword" , "A small spring flower" .)