It had a flight of fancy (3)
I believe the answer is:
roc
'it had a flight of fancy' is the definition.
The definition suggests a singular noun which matches the answer.
This is the entire clue.
Can you help me to learn more?
(Other definitions for roc that I've seen before include "Fabulous giant bird of Eastern legend" , "Vast legendary bird" , "Bird imagined" , "Fabulous Eastern bird of some ferocity" , "Giant mythical bird" .)