Fancy ideas in bed? (5)
I believe the answer is:
dream
'fancy' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for dream that I've seen before include "Cherished hope; reverie" , "Aspiration" , "Sleeping experience" , "It's experienced during sleep" , "Bedroom vision?" .)