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 an anagram.
'repair' is an anagram of 'RAPIER'.
'in' acts as a 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" .)