Inorganic substance (7)
I believe the answer is:
mineral
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">inorganic substance</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 mineral that I've seen before include "Substance that is (usually) inorganic" , "Metal ore" , "Substance needed for health; ore" , "Gypsum or magnesia, say" , "Zinc or magnesium, say" .)