Bitterly cold (3)
I believe the answer is:
icy
'bitterly cold' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for icy that I've seen before include "Posing danger on the road" , "Glacial" , "Very chilly" , "Freezing and slippy" , "frozen over!" .)