American nun addressed letters from old country (4)
I believe the answer is:
ussr
'country' is the definition.
(USSR is an example)
'american nun addressed letters from old' is the wordplay.
I cannot really understand how this works, but
'american' could be 'us' (abbreviation for United States) and 'us' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ussr that I've seen before include "Country established in1922 and dissolved in 1991, in short" , "Former soviet states" , "Former federation of Russial and other states" , "Former union of socialist republics" , "Former association of communist republics" .)