Game, sick one, included by poets (9)
I believe the answer is:
billiards
'game' is the definition.
(I know that billiards is a type of table game)
'sick one included by poets' is the wordplay.
'sick' becomes 'ill' (similar in meaning).
'one' becomes 'i' (Roman numeral).
'included by' is an insertion indicator.
'poets' becomes 'bards' (bard is a kind of poet).
'ill'+'i'='illi'
'illi' inserted inside 'bards' is 'BILLIARDS'.
(Other definitions for billiards that I've seen before include "Game with three balls" , "Indoor sport" , "Table game at which Mary Queen of Scots excelled" , "Ball game" , "Game played with balls on table with pockets" .)