Nail smoother
I believe the answer is:
'nail smoother' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for emery that I've seen before include "Abrasive powder" , "Hard grey-black mineral used as an abrasive" , "hard stuff" , "Abrasive material" , "Coating on paper used as an abrasive" .)