Support the other side (4)
I believe the answer is:
back
I believe this is a double definition.
'support' is the first definition.
(to back is to support or endorse)
'other side' is the second definition.
(the back of something)
'the' is the link.
(Other definitions for back that I've seen before include "player in line of defence?" , "Support - defender - reverse" , "Fashionable again" , "Support - football player" , "Support; footballer" .)