Remain in support (4)
I believe the answer is:
stay
I believe this clue is a double definition.
'remain' is the first definition.
(I know that remain can be written as stay)
'support' is the second definition.
(stay is a kind of support)
'in' is the link.
(Other definitions for stay that I've seen before include "control" , "Stanchion" , "Supporting rod" , "Defer" , "Remain behind" .)