It comes down hard! (4)
I believe the answer is:
hail
'it comes down hard' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hail that I've seen before include "Shower of ice pellets" , "come down hard" , "Hard Rain?" , "Frozen rain or Roman greeting" , "Precipitating ice pellets" .)