Concept album -- a corker -- possibly featuring old piano (4,5)

I believe the answer is:

rock opera

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'concept album' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'a corker possibly featuring old piano' is the wordplay.
'possibly' indicates anagramming the letters.
'featuring' indicates putting letters inside.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'piano' becomes 'p' (musical abbreviation).
'a'+'corker'='acorker'
'acorker' is an anagram of 'rockera'.
'o'+'p'='op'
'rockera' enclosing 'op' is 'ROCK OPERA'.

Can you help me to learn more?

(Other definitions for rock opera that I've seen before include "Show" , "Tommy, for example" .)

I've seen this clue in The Telegraph.

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