Abrasive substance (5)
I believe the answer is:
emery
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">abrasive substance</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for emery that I've seen before include "Abrasive material" , "Abrasive powder" , "Hard black-grey mineral used in grinding and polishing" , "Black abrasive" , "old comedian" .)