Reportedly regretted being discourteous (4)
I believe the answer is:
'discourteous' is the definition.
(I've seen this before)
'reportedly regretted' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'regretted' becomes 'rued' ('rue' can be a synonym of 'regret').
'rued' sounds like 'RUDE'.
'being' is the link.
(Other definitions for rude that I've seen before include "Ill-mannered; hearty" , "Primitive; impolite" , "Impolite; unpolished" , "Impolite or vulgar" , "likely to offend" .)