An eccentric snooker player may
I believe the answer is:
screwball
'an eccentric' is the definition.
(screwball is a kind of eccentric)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for screwball that I've seen before include "odd fellow?" , "Crazy American" , "Wacky" , "Odd person" , "Freak" .)