Evil One stopping poet's game (9)
I believe the answer is:
billiards
'game' is the definition.
(billiards is a kind of game)
'evil one stopping poet's' is the wordplay.
'evil' becomes 'ill' (I've seen this in other clues**).
'one' becomes 'i' (Roman numeral).
'stopping' indicates putting letters inside (stopping can mean blocking a gap).
'poet's' becomes 'bards' (bard is a kind of poet).
'ill'+'i'='illi'
'illi' put inside 'bards' is 'BILLIARDS'.
(Other definitions for billiards that I've seen before include "Game played with balls on table with pockets" , "Table game at which Mary Queen of Scots excelled" , "Ball game" , "Game with three balls" , "Indoor sport" .)