Cinder (5)
I believe the answer is:
ember
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cinder</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for ember that I've seen before include "what causes a warm glow" , "Glowing cinder" , "Remnant of bonfire" , "Fire remnant" , "One smouldering" .)