Lessons about girls (7)

I believe the answer is:

classes

'lessons' is the definition.
(as in school classes)

'about girls' is the wordplay.
'about' becomes 'c' (abbreviation for 'circa').
'girls' becomes 'lasses' (lass can mean a girl).
'c'+'lasses'='CLASSES'

(Other definitions for classes that I've seen before include "Categories" , "Groups with the same social or economic status" , "See 1" .)

I've seen this clue in The Telegraph.

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