Country people appearing in part of opera (7)
I believe the answer is:
armenia
'country' is the definition.
(I've seen this before)
'people appearing in part of opera' is the wordplay.
'people' becomes 'men' (man is a kind of person).
'appearing in' is an insertion indicator.
'part of opera' becomes 'aria' ('aria' is part of 'opera').
'men' placed inside 'aria' is 'ARMENIA'.
(Other definitions for armenia that I've seen before include "Landlocked country of southwest Asia" , "Landlocked country south of Georgia" , "Republic formerly in the USSR" , "South-west Asian country, capital Yerevan" , "Transcaucasian nation" .)