Society described by letter (10)

I believe the answer is:

permissive

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'society described' is the definition.
I can't judge whether this defines the answer.

'by letter' is the wordplay.
'by' becomes 'per' (I've seen this in another clue).
'letter' becomes 'missive' (synonyms).
'per'+'missive'='PERMISSIVE'

Can you help me to learn more?

(Other definitions for permissive that I've seen before include "Like our society" , "granting authorisation" , "Liberal, broad-minded" , "Free" , "Lenient, indulgent" .)

I've seen this clue in The Globe and Mail.

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