Grind harshly (5)
I believe the answer is:
grate
'grind harshly' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for grate that I've seen before include "Shred - jar" , "Rasp; shred" , "Grind (teeth)" , "Make a harsh rasping sound" , "Grind (cheese)" .)