Not fighting the doctor's decision to keep one in bed? (6,2,5,4)

I believe the answer is:

taking it lying down

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'not fighting the doctor's decision to keep one in bed?' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'one in bed?' is the wordplay.
'one' becomes 'takingit' (I can't explain this - if you can you should give a lot more credence to this answer).
'in bed?' becomes 'lying down' (I've seen this before).
'takingit'+'lyingdown'='TAKING IT LYING DOWN'

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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