Sorry, repentant (6)
I believe the answer is:
rueful
I believe this clue is a double definition.
'sorry' is the first definition.
(synonyms)
'repentant' is the second definition.
(similar in meaning)
(Other definitions for rueful that I've seen before include "Melancholy" , "In a sorry state!" , "Penitent" , "Apologetic" , "Full of regret" .)