Nail file material (5)
I believe the answer is:
'nail file material' 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 "Rock used as abrasive" , "Coating on paper used as an abrasive" , "Abrasive powder" , "old comedian" , "Hard black-grey mineral used in grinding and polishing" .)