The most common and most likely answer to this crossword clue is the 9 letter word REPENTANT
R
E
P
E
N
T
A
N
T
More clues leading to the result REPENTANT
- Extremely rare swan with brown cygnet finally remorseful
- Behind bars again, worker's full of regret
- Contrite theatre worker touring hospital department
- Hospital department keeping troubled parent outside is sorry
- Sorry parent with ten kids around
- Chastened about jailed worker
- Transformed Peter, new within, an adherent ultimately sorry for sin
- Sorry writer volunteers to appear in break
- Sorry about dog maybe biting indefinite number attending function
- Writer in film cuts tirade characterising guilt-ridden criminal?
Buddy explains!

The straight part
We know that "characterising guilt-ridden criminal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case characterising guilt-ridden criminal = repentant.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does REPENTANT mean?
REPENTANT noun- One who repents; a penitent.
- Feeling or showing sorrow for wrongdoing.