The most common and most likely answer to this crossword clue is the 6 letter word CHOLER
I've seen this crossword clue in The Times
C
H
O
L
E
R
More clues leading to the result CHOLER
Buddy explains!
The straight part
We know that "irritability" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case irritability = choler.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 CHOLER mean?
CHOLER noun- Anger or irritability.
- One of the four humours of ancient physiology, also known as yellow bile.