Tend to slope (7)
I believe the answer is:
incline
This clue is a double definition.
'tend' is the first definition.
(synonyms)
'slope' is the second definition.
(synonyms)
'to' acts as a link.
(Other definitions for incline that I've seen before include "Gradient" , "Bend forwards" , "List" , "Tend; lean" , "lean forward" .)