Operetta composer in memory supplied by Austrian composer (7)
I believe the answer is:
romberg
'composer' is the definition.
(I know that Romberg is a composer)
'operetta composer in memory supplied by austrian' is the wordplay.
I cannot quite understand how this works, but
'composer' could be 'berg' (Alban Berg, 1885 - 1935) and 'berg' is found within the answer.
'memory' could be 'rom' (Read-Only Memory on a computer) and 'rom' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for romberg that I've seen is " Operettist".)