A tree leaning over a ramp perhaps (8,5)

'a ramp perhaps' is the definition.
(ramp is a kind of inclined plane)

'a tree leaning over' is the wordplay.
'a tree' becomes 'plane' (plane is a type of tree).
'leaning' becomes 'inclined' (similar in meaning).
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
'plane' put after 'inclined' is 'INCLINED PLANE'.