Preside (9)
I believe the answer is:
officiate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">preside</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for officiate that I've seen before include "Perform legal duties" , "Conduct ceremony" , "Take chair" .)