Transformed when carved (4)
I believe the answer is:
hewn
'carved' is the definition.
(I've seen this before)
'transformed when' is the wordplay.
'transformed' indicates an anagram.
'when' anagrammed gives 'HEWN'.
(Other definitions for hewn that I've seen before include "(Of wood) cut, chopped" , "Cut with an axe or chisel" , "Chopped roughly" , "Cut - carved - chopped" , "Sculpted" .)