Slope; tower (4)
I believe the answer is:
rise
This clue is a double definition.
'slope' is the first definition.
(I know that slope can be written as rise)
'tower' is the second definition.
(I've seen this before)
(Other definitions for rise that I've seen before include "Move upward" , "Soar" , "Ascend" , "Get or stand up" , "Rebel" .)