Was sorry, we hear, for being impolite (4)
I believe the answer is:
rude
'being impolite' is the definition.
(similar in meaning)
'was sorry we hear' is the wordplay.
'was sorry' becomes 'rued ' (I've seen this in another clue).
'we hear' indicates a 'sounds like' (homophone) clue.
'rued' sounds like 'RUDE'.
'for' is the link.
(Other definitions for rude that I've seen before include "likely to offend" , "lacking refinement" , "Base" , "Robust - roughly made" , "Coarse, unpolished" .)