What’s coming off a track as a result of cracks? (6,8)

I believe the answer is:

canned laughter

'track as a result of cracks?' is the definition.
I know nothing about this answer so I cannot judge whether this works.

'what's coming off a' is the wordplay.
I cannot quite see how this works, but
'a' could be 'an' and 'an' is found within the answer.
This may be the basis of clue (or it may be nonsense).

(Another definition for canned laughter that I've seen is " Audience reaction added to studio soundtrack".)

I've seen this clue in The Times.

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