Keep up support (8)
I believe the answer is:
maintain
I believe this clue is a double definition.
'keep up' is the first definition.
(I know that keep up can be written as maintain)
'support' is the second definition.
(I've seen this before)
(Other definitions for maintain that I've seen before include "declare" , "Keep in a certain state" , "Keep up - carry on" , "Look after the upkeep" , "Preserve or insist" .)