Social conventions further south (5)

I believe the answer is:

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'social conventions' is the definition.
'mores' can be an answer for 'conventions' (I've seen this before). I am unsure of the 'social' bit.

'further south' is the wordplay.
'further' becomes 'more' ('more' can be a synonym of 'further').
'south' becomes 's' ('S' can be a synonym of 'south').
'more'+'s'='MORES'

Can you help me to learn more?

(Other definitions for mores that I've seen before include "of St Thomas's" , "Social customs of a group" , "Fundamental values of a group" , "Conventions, manners" , "Way of life" .)

I've seen this clue in the Evening Standard.

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