CBS tutor drunk in bar (8)
I believe the answer is:
obstruct
'bar' is the definition.
(thesaurus)
'cbs tutor drunk' is the wordplay.
'drunk' is an anagram indicator.
'cbs'+'tutor'='cbstutor'
'cbstutor' with letters rearranged gives 'OBSTRUCT'.
'in' acts as a link.
(Other definitions for obstruct that I've seen before include "Stymie" , "Hamper" , "Prevent or hinder movement" , "Block the passage or shut out the view" , "Block, hinder" .)