Margaret covering one with Nancy's black dressing-gown (8)

I believe the answer is:

peignoir

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'dressing-gown' is the definition.
I can't tell whether this defines the answer.

'margaret covering one with nancy's black' is the wordplay.
'margaret' becomes 'Peg' (nickname for someone called Margaret).
'covering' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'with' says to put letters next to each other.
'nancy's black' becomes 'noir' ('black' in French, eg in the city of Nancy).
'peg' placed around 'i' is 'peig'.
'peig'+'noir'='PEIGNOIR'

Can you help me to learn more?

(Other definitions for peignoir that I've seen before include "Woman's loose full dressing gown" , "bathrobe" , "Loose dressing-gown" , "Woman's light dressing-gown" , "habit" .)

I've seen this clue in The Independent.

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