Regretted being rushed, disheartened (4)
I believe the answer is:
rued
'regretted' is the definition.
(I've seen this before)
'rushed disheartened' is the wordplay.
'disheartened' means to remove the middle letters.
'rushed' with its centre removed is 'RUED'.
'being' is the link.
(Other definitions for rued that I've seen before include "Bitterly regretted" , "Was sorry" , "was remorseful" , "'Regretted, repented (4)'" , "Was contrite about" .)