Together with; advantage (4)
I believe the answer is:
plus
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">together with</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">advantage</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(a plus is an advantage or benefit)</span><br/ ><br/ ></span>
(Other definitions for plus that I've seen before include "Positive and not a negative" , "Added extra" , "Advantage; also" , "Distant" , "To the French it's more" .)