The most common and most likely answer to this crossword clue is the 7 letter word SOUREST
I've seen this crossword clue in The Guardian
S
O
U
R
E
S
T
More clues leading to the result SOUREST
Buddy explains!
The straight part
We know that "Most peevish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case most peevish = sourest.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 SOUREST mean?
SOUREST adjective- Having an acidic, sharp or tangy taste.
- Made rancid by fermentation, etc.
- Tasting or smelling rancid.
- (of a person's character) Peevish or bad-tempered.
- (of soil) Excessively acidic and thus infertile.
- (of petroleum) Containing excess sulfur.
- Unfortunate or unfavorable.
- Off-pitch, out of tune.