Appreciably cold (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
chilly
'appreciably cold' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for chilly that I've seen before include "Without warmth" , "Quite cold" , "(Of weather) bracing" , "Descriptive of cold weather" , "Nippy" .)