Freezing cold, like small mountains (6)
I believe the answer is:
chilly
'freezing' is the definition.
(I've seen this before)
'cold like small mountains' is the wordplay.
I cannot really see how this works, but
'cold' could be 'chill' (chill can mean cold) and 'chill' is located in the answer.
'like' could be 'y' (similar in meaning) and 'y' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for chilly that I've seen before include "Quite cold" , "unwelcoming" , "Rather cold" , "(Of weather) bracing" , "Unpleasantly cold - sounds like hot stuff" .)