The most common and most likely answer to this crossword clue is the 5 letter word TESTY
I've seen this crossword clue in The Times
T
E
S
T
Y
More clues leading to the result TESTY
- Cross river close to Romsey
- Maybe oral fluency? Ultimately likely to lose it
- Irritable match ending in acrimony
- The empty pen is scratchy
- Check back of vestry for cross
- Irritable, youth leader after trial
- Bad-tempered youth’s first after examination
- Impatient with lots of exams, perhaps
- Before close of play, cricket match becomes bad-tempered
- Snappy as a game of cricket?
Buddy explains!

The straight part
We know that "Irritable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case irritable = testy.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 TESTY mean?
TESTY adjective- Easily annoyed, irritable.
- Marked by impatience or ill humor.