Incandescent (3,3)
I believe the answer is:
red hot
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">incandescent</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for red hot that I've seen before include "Fiercely glowing" , "with enthusiasm?" , "highly emotional" , "sort of poker" , "Strongly fancied to win" .)