Dream of clock perhaps on top of abbey (7)
I believe the answer is:
chimera
'dream' is the definition.
(I have seen 'wild dream' mean 'chimera' so perhaps 'dream' could also mean 'chimera')
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for chimera that I've seen before include "Fire-breathing female monster" , "Wild creation of mind, or monster of Greek myth" , "Fantastic creation of the mind, like Greek mythical monster" , "fake image" , "Illusion" .)