What snooker player does the wrong way round in bar (4)
I believe the answer is:
stop
'bar' is the definition.
(thesaurus)
'what snooker player does the wrong way round' is the wordplay.
'what snooker player does' becomes 'pots'.
'the wrong way round' shows that the letters should be reversed in order.
'pots' written backwards gives 'STOP'.
'in' is the link.
(Other definitions for stop that I've seen before include "cut out" , "Intercept" , "Pause - prevent" , "colon, say" , "Arrest" .)