Punk rocker with condom off (6,6)

I believe the answer is:

johnny rotten

I'm a little stuck... Click here to teach me more about this clue!

'punk rocker with condom' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'off' is the wordplay.
I cannot quite see how this works, but
'off' could be 'rotten' (I've seen this before) and 'rotten' is located in the answer.
The remaining letters 'johnny' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?

I've seen this clue in The Independent.

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