Cold and unfriendly (6)
I believe the answer is:
frosty
'cold and unfriendly' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for frosty that I've seen before include "Lacking in warmth" , "showing little enthusiasm" , "Chilly in attitude, like musical snowman" , "Cold and unfriendly (glance or reception?)" , "Icy cold" .)