Green site redeveloped as a national park (9)
I believe the answer is:
serengeti
'a national park' is the definition.
(I've seen this before)
'green site redeveloped' is the wordplay.
'redeveloped' indicates anagramming the letters.
'green'+'site'='greensite'
'greensite' is an anagram of 'SERENGETI'.
'as' acts as a link.
(Other definitions for serengeti that I've seen before include "region in Tanzania" , "Tanzanian national park area" , "African ecosystem" , "Tiger seen in Tanzania's great National Park" , "where lion holds sway?" .)