Country song that's swell at first? Not quite! (8)
I believe the answer is:
bulgaria
'country' is the definition.
(Bulgaria is an example)
'song that's swell at first? not quite' is the wordplay.
I cannot really understand how this works, but
'song' could be 'aria' (piece of music in an opera) and 'aria' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for bulgaria that I've seen before include "European country - Wombles' great uncle" , "Its capital is Sofia" , "Southeast European country" , "Romania's southern neighbour" , "European republic" .)