Greets with note about sign of cold weather (9)
I believe the answer is:
hailstone
'sign of cold weather' is the definition.
(I've seen this before)
'greets with note about' is the wordplay.
'greets' becomes 'hails' (hailing is a kind of greeting).
'with' is a charade indicator (letters next to each other).
'about' is an anagram indicator.
'note' anagrammed gives 'tone'.
'hails'+'tone'='HAILSTONE'
(Other definitions for hailstone that I've seen before include "bit icy" , "sign of cold weather" , "It lands with a noise" , "Frozen raindrop" , "Small pellet of ice" .)