Four voices in noisy combination (10)

I believe the answer is:

vociferous

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'four voices in noisy combination' is the definition.
I can't judge whether this defines the answer.

'four voices in noisy combination' is the wordplay.
'four voices' can be anagrammed to 'VOCIFEROUS'.
However, I'm unsure how the anagram is indicated.

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(Other definitions for vociferous that I've seen before include "loud" , "Strident" , "Insistently noisy" .)

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

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