The most common and most likely answer to this crossword clue is the 6 letter word ACETIC
I've seen this crossword clue in Financial Times
A
C
E
T
I
C
More clues leading to the result ACETIC
- Such as vinegar, excellent applied to nervous condition
- Abstainer dropping special sort of acid
- Acid makes Spartan lose his head?
- One getting over show of nerves can be really sour
- Vinegary old hermit’s no saint
- Tart topping almost instant
- Call about to turn sour
- Call round in pursuit of a cold tart
- Acid drops in Palace ticket office
- American state with cold upside-down tart
Buddy explains!
The straight part
We know that "really sour" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case really sour = acetic.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 ACETIC mean?
ACETIC adjective- Of, pertaining to, or producing vinegar
- Of or pertaining to acetic acid or its derivatives