Physical material (9)
I believe the answer is:
substance
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">physical material</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 substance that I've seen before include "wealth" , "power" , "Property" , "Subject matter" , "Basic matter" .)