Ring artist for fantastic idea (7)
I believe the answer is:
chimera
'fantastic idea' is the definition.
(chimera can mean a dream or fantasy)
'ring artist' is the wordplay.
'ring' becomes 'chime' (eg a bell chimes or rings).
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'chime'+'ra'='CHIMERA'
'for' is the link.
(Other definitions for chimera that I've seen before include "Fire-breathing female monster" , "Illusory goal; monster" , "eaders of radio appear after jingle" , "Mythical monster, part lion, goat and serpent" , "fabulous beast" .)