Cultivation of incline on top of hill (5)
I believe the answer is:
tilth
'cultivation' is the definition.
(thesaurus)
'incline on top of hill' is the wordplay.
'incline' becomes 'tilt' (I've seen this before**).
'on top of' suggests taking the first letters (I've seen 'on top' mean this).
The initial letter of 'hill' is 'h'.
'tilt'+'h'='TILTH'
'of' is the link.
(Other definitions for tilth that I've seen before include "Ploughed land" , "Cultivate" , "Arable land that is worked by ploughing and sowing" , "Sort of soil" , "sow here" .)