Like an Arctic winter (5)
I believe the answer is:
harsh
'like an arctic winter' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for harsh that I've seen before include "Jarring" , "Unpleasantly stern" , "'Severe, rough (5)'" , "Abrasive, rough or unkind" , "Strident" .)