Rugby players drinking and behaving cheerily (12)

I believe the answer is:

backslapping

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'behaving cheerily' is the definition.
I can't judge whether this definition defines the answer.

'rugby players drinking' is the wordplay.
'rugby players' becomes 'backs' (back is a type of rugby player).
'drinking' becomes 'lapping' (lapping is a kind of drinking).
'backs'+'lapping'='BACKSLAPPING'

'and' is the link.

Can you help me to learn more?

(Other definitions for backslapping that I've seen before include "Demonstratively cheery" , "Hearty" .)

I've seen this clue in The Times.

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