Grinding tooth (5)
I believe the answer is:
molar
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">grinding tooth</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for molar that I've seen before include "Dealing with masses" , "Broad-crowned tooth" , "Type of tooth" , "of ivory, perhaps" , "part of the daily grind" .)