Cultivated green site in African National Park (9)
I believe the answer is:
serengeti
'african national park' is the definition.
(Tanzanian national park)
'cultivated green site' is the wordplay.
'cultivated' is an anagram indicator.
'green'+'site'='greensite'
'greensite' is an anagram of 'SERENGETI'.
'in' acts as a link.
(Other definitions for serengeti that I've seen before include "African ecosystem" , "reserve for game" , "Tanzanian wildlife area" , "area of Tanzania" , "Tiger seen in Tanzania's great National Park" .)