Country fellows breaking into song (7)
I believe the answer is:
'country' is the definition.
(Armenia is a country)
'fellows breaking into song' is the wordplay.
'fellows' becomes 'men' (fellow can mean a man).
'breaking into' indicates putting letters inside.
'song' becomes 'aria' (aria is a kind of song).
'men' put inside 'aria' is 'ARMENIA'.
(Other definitions for armenia that I've seen before include "Former Russian republic, its capital Yerevan" , "Republic in N W Asia" , "Landlocked country south of Georgia" , "Landlocked country, an Asian soviet before 1991, capital Yerevan" , "Republic formerly in the USSR" .)