Just, simply (4)
I believe the answer is:
only
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">just</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">simply</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for only that I've seen before include "Except that; single" , "Exclusive - individual" , "Merely; single" , "Siblingless (child)" , "Alone; solitary" .)