Performing twice in Tosca is stimulating for a soloist? (9)

I believe the answer is:

onanistic

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'stimulating for a soloist?' is the definition.
I can't judge whether this defines the answer.

'performing twice in tosca' is the wordplay.
'twice in' means two substitutions for 'in'.
'performing' indicates anagramming the letters (the letters move around or 'perform').
'in'+'in'+'tosca'='inintosca'
'inintosca' anagrammed gives 'ONANISTIC'.

'is' acts as a link.

Can you help me to learn more?

I've seen this clue in The Guardian.

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