Unexpectedly needing a forte — or even louder? (9)

I believe the answer is:

deafening

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'even louder?' is the definition.
I can't tell whether this definition defines the answer.

'unexpectedly needing a forte' is the wordplay.
'unexpectedly' indicates anagramming the letters.
'forte' becomes 'f' (music abbreviation - loud).
'needing'+'a'+'f'='needingaf'
'needingaf' with letters rearranged gives 'DEAFENING'.

'or' is the link.

Can you help me to learn more?

(Other definitions for deafening that I've seen before include "Noisy" , "Very loud" .)

I've seen this clue in The Times.

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