Children's story, just fiction (3)
I believe the answer is:
lie
'fiction' is the definition.
(I've seen this in other clues)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for lie that I've seen before include "Couch" , "False statement" , "Assume recumbent posture" , "Prevaricate or recline" , "Tell porkies" .)