Regretted being rushed, disheartened (4)
I believe the answer is:
rued
'regretted' is the definition.
('rue' can be a synonym of 'regret')
'rushed disheartened' is the wordplay.
'disheartened' says to hollow out the word (remove centre letters) (the middle or heart is removed).
'rushed' with its middle 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" .)