Strong fire (5)
I believe the answer is:
blaze
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">strong fire</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 blaze that I've seen before include "brilliant" , "Fierce fire" , "Burn brightly" , "Pioneer" , "Strong flame burning brightly" .)