Determined to include wild green island in African ecosystem (9)
I believe the answer is:
serengeti
'african ecosystem' is the definition.
(I've seen this before)
'determined to include wild green island' is the wordplay.
'determined' becomes 'set' ('set' can be a synonym of 'determined').
'to include' indicates putting letters inside.
'wild' indicates an anagram.
'island' becomes 'i'.
'green' is an anagram of 'renge'.
'set' placed around 'renge' is 'serenget'.
'serenget'+'i'='SERENGETI'
'in' acts as a link.
(Other definitions for serengeti that I've seen before include "Tanzanian wildlife area" , "place to watch game" , "Vast plain" , "African ecosystem" , "Tanzanian national park area" .)