Pretend to be a writer, young one imprisoned here? (7)

I believe the answer is:

playpen

'young one imprisoned here?' is the definition.

'pretend to be a writer' is the wordplay.
'pretend to be' becomes 'play'.
'a writer' becomes 'pen' (I've seen this before).
'play'+'pen'='PLAYPEN'

(Other definitions for playpen that I've seen before include "Nipper stuck here" , "juvenile restraint" , "Child's enclosure" , "Toddler's enclosure" , "Enclosure for child" .)

I've seen this clue in The Times.

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