Ladies back adopting new jargon (5)
I believe the answer is:
slang
'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'.
Can you help me to learn more?
(Other definitions for slang that I've seen before include "abuse" , "common language" , "Informal language - jargon" , "Insult" , "Be abusive" .)