Start, commence (5)
I believe the answer is:
begin
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">start</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that start is a kind of begin)</span><br/ ><br/ >'<span class="explanation-format__original">commence</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that commence is a kind of begin)</span><br/ ><br/ ></span>
(Other definitions for begin that I've seen before include "Institute" , "Make a start" , "former Israeli Nobel peace prize winner" , "Launch" , "Monachem --" .)