Fancy that's first bell? (7)
I believe the answer is:
chimera
'fancy' is the definition.
(chimera can mean a fancy or delusion)
'that's first bell?' is the wordplay.
'that' becomes 'ra' (I can't justify this - if you can you should believe this answer much more).
'first' says to put letters next to each other.
'bell?' becomes 'chime' (synonyms).
'ra' put after 'chime' is 'CHIMERA'.
Can you help me to learn more?
(Other definitions for chimera that I've seen before include "Race him (anag.)" , "Mythical monster, part lion, goat and serpent" , "wild dream" , "Illusory achievement; mythical beast" , "Vain, foolish, or incongruous fancy" .)