The most common and most likely answer to this crossword clue is the 9 letter word PETULANCE
I've seen this crossword clue in The Times
P
E
T
U
L
A
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C
E
More clues leading to the result PETULANCE
- Favourite weapon to contain universal ill-humour
- Favourite cryptic clue about an irritable mood
- Favourite uncle hurt about aunt’s initial pique
- Distributed tape with uncle showing peevish irritation
- Bad temper in scheme restricting English trade union and church
- Stroke uncle with a ruptured spleen
- Favourite uncle somehow hiding a bad temper
- ‘Downtown’ performer pleasant, not one for sulkiness
- Ill-humour universal when nailed by weapon of choice?
- Bad temper shown by alien in rising up with weapon
Buddy explains!

The straight part
We know that "ill-humour" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ill-humour = petulance.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 PETULANCE mean?
PETULANCE noun- Rudeness, insolence.
- An insolent remark or act.
- Childish impatience or sulkiness; testiness.