Delusion, fantasy (8)
I believe the answer is:
illusion
I believe this clue is a double definition.
'delusion' is the first definition.
(thesaurus)
'fantasy' is the second definition.
(synonyms)
(Other definitions for illusion that I've seen before include "False idea or conjuring trick" , "Fantasy or mirage" , "Deceptive appearance" , "Mocking old" , "A false belief about linus oil" .)