Frivolous (5-6)
'frivolous' is the definition.
(light can mean trivial or unimportant)
This is the entire clue.
(Other definitions for light that I've seen before include "Source of illumination" , "Frivolous -- insubstantial" , "Not too demanding" , "skedaddle!" , "bulb" .)
'frivolous' is the definition.
(similar in meaning)
This is the entire clue.
(Other definitions for trivial that I've seen before include "Piddling" , "lacking weight" , "Footling" , "Rival it, being unimportant" , "Of little consequence" .)
'frivolous' is the definition.
(similar in meaning)
This is the entire clue.
(Other definitions for flighty that I've seen before include "Capricious" , "rather impetuous?" , "Fickle; erratic" , "Changeable" , "Frivolous - irresponsible" .)
'frivolous' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for empty-headed that I've seen before include "Scatterbrained" , "Given to frivolity" , "Vacuous" , "Frivolous" , "Unintelligent, stupid" .)