Development of eastern nation (6)
I believe the answer is:
estate
'development' is the definition.
(thesaurus)
'eastern nation' is the wordplay.
'eastern' becomes 'e'.
'nation' becomes 'state' ('state' can be a synonym of 'nation').
'e'+'state'='ESTATE'
'of' acts as a link.
(Other definitions for estate that I've seen before include "Person's belongings after death" , "Property with large grounds" , "Rank - housing development - car" , "Piece of land with a large house or many small ones" , "Plantation" .)