Cut down when damaged (4)
I believe the answer is:
hewn
'cut down' is the definition.
('hewn' can be a synonym of 'cut down')
'when damaged' is the wordplay.
'damaged' indicates an anagram.
'when' anagrammed gives 'HEWN'.
(Other definitions for hewn that I've seen before include "Hacked" , "Cut - carved - chopped" , "(Of wood) cut, chopped" , "Cut with an axe or chisel" , "Felled" .)