Was remorseful (4)
I believe the answer is:
rued
'was remorseful' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for rued that I've seen before include "Bitterly regretted" , "'Regretted, repented (4)'" , "was remorseful" , "Was sorry" , "Was contrite about" .)