Manicurist's board (5)
I believe the answer is:
emery
'manicurist's board' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for emery that I've seen before include "Abrasive material" , "Abrasive powder" , "Abrasive form of corundum" , "hard stuff" , "Hard, grey-black mineral used as 11 down" .)