Fire-resistant mineral (8)
I believe the answer is:
asbestos
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fire-resistant mineral</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 asbestos that I've seen before include "Insulating mineral" , "I might end up lagging" , "Fire defence" , "dangerous dust" , "condemned building material" .)