Support front? No! (4)
I believe the answer is:
back
I believe this is a double definition.
'support' is the first definition.
(back is a kind of support)
'front? no' is the second definition.
('back' is the opposite to 'front')
(Other definitions for back that I've seen before include "Second" , "Stern" , "See 17" , "Golf holes 10-18" , "Support (from behind?)" .)