Attacked them for terrible duets, alas (9)

I believe the answer is:

assaulted

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'attacked' is the definition.
('assault' can be a synonym of 'attack')

'terrible duets alas' is the wordplay.
'terrible' indicates an anagram.
'duets'+'alas'='duetsalas'
'duetsalas' anagrammed gives 'ASSAULTED'.

'them for' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?

(Another definition for assaulted that I've seen is " Attacked violently".)

I've seen this clue in The Irish Times.

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