Alight, burning (5)
I believe the answer is:
afire
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">alight</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">burning</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(on fire)</span><br/ ><br/ ></span>
(Other definitions for afire that I've seen before include "in flames" , "Alight" , "Burning" , "Ablaze" , "Blazing - excited" .)