Prankster's project (4)
I believe the answer is:
hoax
'prankster's project' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hoax that I've seen before include "A joking kind of deception" , "Leg-pull" , "Playful fraud" , "Humorous or malicious deception" , "Kid" .)