Greeting on street, one that is icy (9)
I believe the answer is:
hailstone
'greeting on street one that is icy' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'greeting on street one' is the wordplay.
'greeting' becomes 'hail' ('hail' is a greeting).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'street' becomes 'st' (abbreviation).
'hail'+'st'+'one'='HAILSTONE'
Can you help me to learn more?
(Other definitions for hailstone that I've seen before include "Frozen raindrop" , "one in the shower" , "Small pellet of ice" , "It lands with a noise" , "sign of cold weather" .)