Spice to grate (6)
I believe the answer is:
nutmeg
'spice to grate' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for nutmeg that I've seen before include "spicy stuff" , "Aromatic spicy kernel" , "Hard seed of tropical tree used as spice" , "Variety of spice" , "Asian tree whose aromatic seed is used as spice when grated or ground" .)