Idealist, visionary (7)
I believe the answer is:
dreamer
This clue is a double definition.
'idealist' is the first definition.
(synonyms)
'visionary' is the second definition.
(dreamer is a kind of visionary)
(Other definitions for dreamer that I've seen before include "He has visions" , "One imagines" , "description of an Oxford spire?" , "One who tends to live in an unreal world" , "One fantasising" .)