Play safe and knock (5,3)

I believe the answer is:

peter pan

'play' is the definition.
(I know that Peter Pan is a play)

'safe and knock' is the wordplay.
'safe' becomes 'peter' (slang term for a safe).
'and' is a charade indicator (letters next to each other).
'knock' becomes 'pan' (both can mean to criticise).
'peter'+'pan'='PETER PAN'

(Other definitions for peter pan that I've seen before include "Youth forever" , "ageless character" , "Ever-young person" , "Type of eternal youth" , "J M Barrie's boy who never grows up" .)

I've seen this clue in The Sunday Times and The Times.

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