Old country reduced area for Bluebeard's Castle, for example (5)
I believe the answer is:
opera
'bluebeard's castle for example' is the definition.
I can't tell whether this definition defines the answer.
'old country reduced area' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'country' becomes 'per' (I can't explain this - if you can you should believe this answer much more).
'reduced' suggests taking the first letters (the word is reduced to its first letter).
The initial letter of 'area' is 'a'.
'o'+'per'+'a'='OPERA'
'for' is the link.
Can you help me to learn more?
(Other definitions for opera that I've seen before include "Stage entertainment" , "Eg, La traviata" , "Carmen, perhaps" , "Musical play" , "Tosca, for example" .)