Land on a site needing development (7)
I believe the answer is:
estonia
'land' is the definition.
(Estonia is a country)
'on a site needing development' is the wordplay.
'needing development' indicates anagramming the letters (letters developed in another way).
'on'+'a'+'site'='onasite'
'onasite' is an anagram of 'ESTONIA'.
(Other definitions for estonia that I've seen before include "Baltic state" , "'So eat in here in Tallinn, say (7)'" , "East European country" , "Nation" , "Republic in northeastern Europe" .)