Sounds like a hit from Bugsy Malone (5)
I believe the answer is:
splat
If this is the answer I cannot explain how the clue works.
Can you help me to learn more?
(Other definitions for splat that I've seen before include "Sound of a wet and squishy impact" , "Noise on landing" , "amusing noise" , "Wet slapping sound" , "Noise of soft wet impact; part of a chair back" .)