Together with; advantage (4)
I believe the answer is:
plus
This clue is a double definition.
'together with' is the first definition.
(I've seen this before)
'advantage' is the second definition.
(a plus is an advantage or benefit)
(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" .)