Vulgar prom ripe for redevelopment (8)
I believe the answer is:
improper
'vulgar' is the definition.
(I've seen this before)
'prom ripe for redevelopment' is the wordplay.
'for redevelopment' is an anagram indicator (I've seen this in other clues).
'prom'+'ripe'='promripe'
'promripe' is an anagram of 'IMPROPER'.
(Other definitions for improper that I've seen before include "Indecent or unsuitable" , "Wrong - unsuitable" , "Naughty" , "Inappropriate" , "Hardly meet" .)