The most common and most likely answer to this crossword clue is the 6 letter word GRUMPY
I've seen this crossword clue in The Guardian
G
R
U
M
P
Y
More clues leading to the result GRUMPY
- Seat in empty gallery likely to snap?
- Petulant medic imbibing spirit before close of party
- Sullen guy keeping queen and politician apart
- Gee! Douglas’ cat is bad-tempered
- Likely to moan from good sex, not half
- Dwarf‘s bottom stuck between edges of gateway
- Cross borne by gutless chap holding back
- Heartless guy, pinching bottom, makes one cross
- Cross empty gallery to take seat
- Fellow loses heart, gets back in a bad mood
Buddy explains!

The straight part
We know that "bad-tempered" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case bad-tempered = grumpy.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 GRUMPY mean?
GRUMPY adjective- Dissatisfied and irritable.