Remaining to one side (4)
I believe the answer is:
left
I believe this clue is a double definition.
'remaining' is the first definition.
(I know that remaining can be written as left)
'to one side' is the second definition.
(left and right)
(Other definitions for left that I've seen before include "Sailed from" , "Withdrew - Labour" , "Vacated; political wing" , "Communist?" , "choice at a junction?" .)