Coating that acts as an abrasive (5)
I believe the answer is:
emery
(Other definitions for emery that I've seen before include "Black abrasive" , "Rock used as abrasive" , "Abrasive powder" , "Dick - - , late comedian" , "hard stuff" .)
I believe the answer is:
emery
(Other definitions for emery that I've seen before include "Black abrasive" , "Rock used as abrasive" , "Abrasive powder" , "Dick - - , late comedian" , "hard stuff" .)