Chart set’s irregularity in product trial (5,4)

I believe the answer is:

crash test

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'chart set's irregularity in product trial' is the definition.
I can't tell whether this defines the answer.

'chart set's irregularity' is the wordplay.
'irregularity' indicates an anagram.
'chart'+'sets'='chartsets'
'chartsets' with letters rearranged gives 'CRASH-TEST'.

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I've seen this clue in The Mirror.

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