Dejected sister, lips quivering (10)

I believe the answer is:

spiritless

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'dejected' is the definition.
(thesaurus)

'sister lips quivering' is the wordplay.
'sister lips' anagrams to 'SPIRITLESS'.
Though, I am not sure how the anagram is indicated.

Can you help me to learn more?

(Another definition for spiritless that I've seen is " Lacking ardour".)

I've seen this clue in The Telegraph.

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