The most common and most likely answer to this crossword clue is the 9 letter word RESENTFUL
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More clues leading to the result RESENTFUL
- Suffering nurse left in high dudgeon
- Envious: regularly seen filling up still
- Comfortable about bridge opponents becoming bitter
- English knight tucking into relaxing bitter
- Quiet about men losing head or feeling bitter?
- Bitter, but relaxed about two points
- Placid about extremes of emotion put out
- Soothing cask of Ensign bitter
- Dispatched again — almost the entire lot was bitter
- Travelling nurse felt put out
Buddy explains!

The straight part
We know that "bitter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bitter = resentful.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 RESENTFUL mean?
RESENTFUL adjective- Inclined to resent, who tends to harbor resentment, when wronged.
- Harboring resentment, full of resentment, at a given moment.