Support in reverse (7)
I believe the answer is:
backing
I believe this is a double definition.
'support' is the first definition.
(I know that support can be written as backing)
'reverse' is the second definition.
(thesaurus)
'in' is the link.
(Other definitions for backing that I've seen before include "promotion" , "Support" , "gambling" , "change of wind" , "on the retreat" .)