Backed America and abandoned another country (5)
I believe the answer is:
sudan
'another country' is the definition.
'sudan' can be an answer for 'country' (Sudan is an example). I am not sure about the 'another' bit.
'backed america and abandoned' is the wordplay.
'backed' says the letters should be written in reverse.
'america' becomes 'US' (United States).
'abandoned' indicates an anagram (the original order is abandoned).
'us' reversed gives 'su'.
'and' with letters rearranged gives 'dan'.
'su'+'dan'='SUDAN'
(Other definitions for sudan that I've seen before include "African country on the Red Sea" , "Country bordering the Red Sea" , "African region" , "NE African country, capital Khartoum" , "Region of Africa" .)