The humour associated with Old Doc's pub on Malta (6)

I believe the answer is:

phlegm

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'the humour associated with old doc's' is the definition.
I can't tell whether this definition defines the answer.

'pub on malta' is the wordplay.
'pub' becomes 'ph' (public house).
'on' becomes 'leg' (cricket term, fielding positions).
'malta' becomes 'm'.
'ph'+'leg'+'m'='PHLEGM'

Can you help me to learn more?

(Other definitions for phlegm that I've seen before include "'spit it out!'" , "Mucus - stolidity" , "Coolness" , "Calmness of temperament" , "Mucus - self-possession" .)

I've seen this clue in The Telegraph.

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