Bar last pair, voicing pique all at once (5)

I believe the answer is:

tutti

'all at once' is the definition.
(musical instruction)

I cannot understand how the remainder of the clue works.

(Other definitions for tutti that I've seen before include "(Musically) all play together" , "Every instrument to play" , "[MUSICIAN] play together" , "All (musical players)" , "Piece together" .)

I've seen this clue in The Guardian.

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