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