Jolly girl hated the changes (12)

I believe the answer is:

lighthearted

'jolly' is the definition.
(thesaurus)

'girl hated the changes' is the wordplay.
'changes' indicates an anagram.
'girl'+'hated'+'the'='girlhatedthe'
'girlhatedthe' is an anagram of 'LIGHTHEARTED'.

(Another definition for lighthearted that I've seen is " Cheerful".)

I've seen this clue in The Times.

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