Sudden bar redevelopment put off (6)
I believe the answer is:
abrupt
'sudden' is the definition.
('abrupt' can be similar in meaning to 'sudden')
'bar redevelopment put off' is the wordplay.
'redevelopment' indicates an anagram.
'off' indicates anagramming the letters.
'bar' with letters rearranged gives 'abr'.
'put' with letters rearranged gives 'upt'.
'abr'+'upt'='ABRUPT'
(Other definitions for abrupt that I've seen before include "Snap!" , "Terse and sudden" , "Impolite" , "Gruff" , "Offhand" .)