Funny, tight-lipped vocalisation made by leader leaving tour. (6)

I believe the answer is:

humour

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'funny tight-lipped vocalisation' is the definition.
The definition suggests a singular noun which matches the answer.

'by leader leaving tour' is the wordplay.
'by' becomes 'hum' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'leader leaving' means to remove the first letter.
'tour' with its first letter taken away is 'our'.
'hum'+'our'='HUMOUR'

'made' acts as a link.

Can you help me to learn more?

(Other definitions for humour that I've seen before include "Hilarity" , "The quality of being funny" , "Wit" , "Bodily fluid" , "Give way to someone's wishes - it's funny" .)

I've seen this clue in The Irish Times.

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