Opera with a lot of musical backing using standards (9)
I believe the answer is:
normative
'opera with a lot of musical backing using standards' is the definition.
I can't tell whether this defines the answer.
'opera with a lot of musical backing' is the wordplay.
'opera' becomes 'norma' (I've seen this in another clue).
'with' means one lot of letters go next to another.
'a lot of musical' becomes 'evit' (I can't justify this - if you can you should give a lot more credence to this answer).
'backing' says the letters should be written backwards.
'evit' back-to-front is 'tive'.
'norma'+'tive'='NORMATIVE'
Can you help me to learn more?
(Another definition for normative that I've seen is " setting a standard".)