Overweight and maybe apt to splutter? (3)
I believe the answer is:
fat
'overweight' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for fat that I've seen before include "As Bunter" , "Portly" , "Greasy substance" , "Profitable" , "Excess body weight" .)