Tooth tissue (7)
I believe the answer is:
dentine
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tooth tissue</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for dentine that I've seen before include "Tin need (anag.)" , "bony material" , "Material in teeth" , "Tooth material" , "which forms tooth" .)