Scoria (4)
I believe the answer is:
slag
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">scoria</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for slag that I've seen before include "Cinders could become this" , "Scum on metal - dissolute woman" , "Smelting or coal waste" , "a girl who puts out" , "Smelted-ore refuse" .)