Sloping, tilting (8)
I believe the answer is:
slanting
I believe this clue is a double definition.
'sloping' is the first definition.
(I know that sloping can be written as slanting)
'tilting' is the second definition.
('slant' can be a synonym of 'tilt')
(Other definitions for slanting that I've seen before include "Leaning, sloping" , "Sloping, tilting" , "not on the level" .)