She upset Carlo at Christmas
I believe the answer is:
carol
'she' is the definition.
'upset carlo at christmas' is the wordplay.
'carlo' can be anagrammed to 'CAROL'.
Though, I am unsure how the anagram is indicated.
Can you help me to learn more?
(Other definitions for carol that I've seen before include "Coral (anag.)" , "Joyful religious song" , "Joyful song - girl's name" , "Girl" , "Song, especially at Christmas" .)