Regretted being impolite to the Speaker (4)
I believe the answer is:
rued
'regretted' is the definition.
('rue' can be a synonym of 'regret')
'impolite to the speaker' is the wordplay.
'impolite' becomes 'rude' (similar in meaning).
'to the speaker' shows a homophone (sound like) (I've seen 'of the speaker' mean this (how the word might sound when spoken)).
'rude' is a homophone of 'RUED'.
'being' is the link.
(Other definitions for rued that I've seen before include "'Regretted, repented (4)'" , "was remorseful" , "Was contrite about" , "Was sorry" , "Bitterly regretted" .)