Winter roof hanging (6)
I believe the answer is:
icicle
'winter roof hanging' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for icicle that I've seen before include "Spear-like shape formed by the freezing of dripping water" , "Hanging drop of cold water" , "Pendent spear of frozen water" , "solidified dripping" , "Frozen water stalactite" .)