Vast wildlife reserve might be the greenest one around. (9)
I believe the answer is:
serengeti
'vast wildlife reserve' is the definition.
'serengeti' can be an answer for 'reserve' (I've seen this before). I am not sure about the 'vast wildlife' bit.
'might be the greenest one around' is the wordplay.
'might be' is an anagram indicator (I've seen this in other clues).
'one' becomes 'unity' (synonyms).
'around' says to take the centre.
The central letter of 'unity' is 'i'.
'greenest' anagrammed gives 'serenget'.
'serenget'+'i'='SERENGETI'
Can you help me to learn more?
(Other definitions for serengeti that I've seen before include "Green ties (anag.)" , "Wildlife-rich region of Africa" , "Tanzanian plain renowned for its wildlife" , "Tanzanian wildlife area" , "Tanzanian national park area" .)