Rebuilt hip bistro must ignore small bar (8)
I believe the answer is:
prohibit
'bar' is the definition.
(thesaurus)
'rebuilt hip bistro must ignore small' is the wordplay.
'rebuilt' indicates anagramming the letters.
'must ignore' is a deletion indicator.
'small' becomes 's' (abbreviation - e.g. clothes size).
'hip'+'bistro'='hipbistro'
'hipbistro' with 's' removed is 'hipbitro'.
'hipbitro' with letters rearranged gives 'PROHIBIT'.
(Other definitions for prohibit that I've seen before include "Forbid, ban" , "Proscribe, forbid" , "Disallow" , "Ban; prevent" , "Stop" .)