Cold metal crushed by giant (6)
I believe the answer is:
biting
'cold' is the definition.
(similar in meaning)
'metal crushed by giant' is the wordplay.
'metal' becomes 'tin' (tin is a kind of metal).
'crushed by' means one lot of letters goes inside another.
'giant' becomes 'big' (similar in meaning).
'tin' placed into 'big' is 'BITING'.
(Other definitions for biting that I've seen before include "Painful or stinging" , "Caustic or cutting - like teeth?" , "(Of wit) harsh, cruel" , "Sarcastic; very cold" , "Acerbic" .)