Raises backs (5)
I believe the answer is:
rears
I believe this is a double definition.
'raises' is the first definition.
(rearing is a kind of raising)
'backs' is the second definition.
('rear' can be a synonym of 'back')
(Other definitions for rears that I've seen before include "Sets up" , "Fosters, brings up" , "bucks" , "Raises" , "Back ends" .)