Nation America backed, and abandoned (5)
I believe the answer is:
sudan
'nation' is the definition.
(Sudan is an example)
'america backed and abandoned' is the wordplay.
'america' becomes 'us' (abbreviation for the United States).
'backed' says the letters should be written in reverse.
'abandoned' indicates an anagram.
'us' in reverse letter order is 'su'.
'and' anagrammed gives 'dan'.
'su'+'dan'='SUDAN'
(Other definitions for sudan that I've seen before include "Recently-split country" , "Us and the African state" , "Sun ad for the African state" , "African region" , "Country between Egypt and Zaire" .)