It's clear-cut as a decisive trial (7,4)

I believe the answer is:

crucial test

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'trial' is the definition.
(thesaurus)

'it's clear-cut as a decisive' is the wordplay.
'it's clear-cut' can be anagrammed to 'CRUCIAL TEST'.
But, I am not sure how the anagram is indicated.

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I've seen this clue in The Globe and Mail.

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