Sets on fire (7)
I believe the answer is:
ignites
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sets on fire</span>' is the definition.<br/ ><span class="explanation-format__explanation">('ignite' can be a synonym of 'set on fire')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ignites that I've seen before include "Catches fire" , "Sets alight" , "lights" , "Sets on fire" .)