Operatic heroine taking in American city (5)
I believe the answer is:
miami
'city' is the definition.
(Miami is an example)
'operatic heroine taking in american' is the wordplay.
'operatic heroine' becomes 'mimi'.
'taking in' is an insertion indicator.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'mimi' placed around 'a' is 'MIAMI'.
(Other definitions for miami that I've seen before include "US town" , "Prejudice in favour of one person or thing" , "Popular city in SE Florida" , "Port in Florida" , "US city" .)