Country song American tenor breaks into (7)
I believe the answer is:
austria
'country' is the definition.
(I know that Austria is a country)
'song american tenor breaks into' is the wordplay.
'song' becomes 'aria' (aria is a kind of song).
'american' becomes 'us' (abbreviation for United States).
'tenor' becomes 't'.
'breaks into' is an insertion indicator.
'us'+'t'='ust'
'aria' placed around 'ust' is 'AUSTRIA'.
(Other definitions for austria that I've seen before include "Landlocked European country" , "Central European republic" , "Find US tiara in this country" , "Central European country" , "Original setting for Mozart" .)