Offensive sign -- until redesigned (9)
I believe the answer is:
insulting
'offensive' is the definition.
('insulting' can be similar in meaning to 'offensive')
'sign until redesigned' is the wordplay.
'redesigned' indicates an anagram.
'sign'+'until'='signuntil'
'signuntil' is an anagram of 'INSULTING'.
(Other definitions for insulting that I've seen before include "Treating with disrespect" , "What offender's doing" , "Offensive" .)