Smelting refuse (4)
I believe the answer is:
slag
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">smelting refuse</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for slag that I've seen before include "Cinders could become this" , "Cinder" , "a girl who puts out" , "Smelted-ore refuse" , "Perfect" .)