Damaged blade is put out of action (7)
I believe the answer is:
disable
'put out of action' is the definition.
(I've seen this before)
'damaged blade is' is the wordplay.
'damaged' indicates anagramming the letters.
'blade'+'is'='bladeis'
'bladeis' is an anagram of 'DISABLE'.
(Other definitions for disable that I've seen before include "For hamstring" , "Make inoperable" , "cripple" , "Weaken" , "Prevent" .)