Unexpectedly together (3,2,4)

I believe the answer is:

all at once

This clue is a double definition.

'unexpectedly' is the first definition.
(thesaurus)

'together' is the second definition.
(I've seen this before)

(Other definitions for all at once that I've seen before include "Without warning" , "Together" , "Simultaneously - immediately" , "in unison" , "Suddenly" .)

I've seen this clue in The Telegraph.

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