A grinder? (5)
I believe the answer is:
molar
'a grinder?' is the definition.
(I know that grinder can be written as molar)
This is all the clue.
(Other definitions for molar that I've seen before include "Type of tooth" , "that could be capped" , "Large tooth" , "part of the daily grind" , "Moral (anag.)" .)