Harmony once cheer broke out (9)

I believe the answer is:

coherence

I'm a little stuck... Click here to teach me more about this clue!

'harmony' is the definition.
(I've seen this in another clue)

'once cheer broke out' is the wordplay.
'once cheer' can be anagrammed to 'COHERENCE'.
However, I'm unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for coherence that I've seen before include "Logical consistency" , "union" , "ability to talk sense" , "sense of unity" , "Sticking together" .)

I've seen this clue in the Sydney Morning Herald.

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