Flighty (6)
I believe the answer is:
fickle
'flighty' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for fickle that I've seen before include "Changeable (with regard to loyalty)" , "Erratic, unpredictable" , "Liable to sudden unpredictable change" , "Prone to shifting loyalties" , "Often changing, not reliable emotionally" .)