Regretted being offensive to the audience (4)
I believe the answer is:
rued
'regretted' is the definition.
('rue' can be a synonym of 'regret')
'offensive to the audience' is the wordplay.
'offensive' becomes 'rude'.
'to the audience' shows a homophone (sound like).
'rude' sounds like 'RUED'.
'being' is the link.
(Other definitions for rued that I've seen before include "was remorseful" , "Was sorry" , "Bitterly regretted" , "Was contrite about" , "'Regretted, repented (4)'" .)