Deep regret as vibrations not leading to ecstasy (7)
I believe the answer is:
remorse
'deep regret' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
(Other definitions for remorse that I've seen before include "display of conscience" , "Guilty conscience" , "it may bite" , "Ruefulness" , "Sorrow for wrongs committed" .)