A tooth (5)
I believe the answer is:
molar
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a tooth</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that molar is a type of tooth)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for molar that I've seen before include "of ivory, perhaps" , "that could be capped" , "Large tooth" , "Chewer and grinder" , "Broad-crowned tooth" .)