Casual friends turning up, like Larry? (9)

I believe the answer is:

slaphappy

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'casual friends turning up like larry?' is the definition.
I can't tell whether this definition defines the answer.

'casual friends turning up' is the wordplay.
'casual friends' becomes 'pals' (pal is a kind of friend. I am not sure about the 'casual' bit.).
'turning' says the letters should be written in reverse.
'up' becomes 'happy' (I've seen this in another clue).
'pals' back-to-front is 'slap'.
'slap'+'happy'='SLAPHAPPY'

Can you help me to learn more?

(Other definitions for slaphappy that I've seen before include "Silly -- unmethodical -- punch-drunk" , "Cheerfully casual" , "Cheerfully irresponsible" , "careless" .)

I've seen this clue in The Times.

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