Issue that's upset girl (5)
I believe the answer is:
susie
'girl' is the definition.
'issue that's upset' is the wordplay.
'that's upset' indicates an anagram.
'issue' is an anagram of 'SUSIE'.
(Other definitions for susie that I've seen before include "Wake Up Little - (Everly Brothers)" , "Tongue-twister sister sewing shirts for soldiers" , "Woman" , "Old song: ''If you knew . . . . . like I know . . . . .''" , "Girl's name" .)