Ladies back adopting new jargon (5)

I believe the answer is:

slang

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'jargon' is the definition.
(synonyms)

'ladies back adopting new' is the wordplay.
'ladies back' becomes 'slag' (I can't justify this - if you can you should believe this answer much more).
'adopting' is an insertion indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'slag' going around 'n' is 'SLANG'.

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(Other definitions for slang that I've seen before include "abuse" , "common language" , "Informal language - jargon" , "Insult" , "Be abusive" .)

I've seen this clue in The Times.

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