Cheerful, which is auspicious (6)
I believe the answer is:
bright
This clue is a double definition.
'cheerful' is the first definition.
(thesaurus)
'auspicious' is the second definition.
(thesaurus)
'which is' is the link.
(Other definitions for bright that I've seen before include "Sparkling" , "Cheerful or quick-witted" , "Vivid - promising - smart" , "Illuminated" , "Radiant -- clever" .)