Worsen, inflame (9)
I believe the answer is:
aggravate
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">worsen</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">inflame</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for aggravate that I've seen before include "Annoy; make worse" , "Make (a problem) worse" , "Make more serious" , "Make a bad situation worse" , "Pester" .)