The most common and most likely answer to this crossword clue is the 4 letter word AURA
I've seen this crossword clue in The Times
A
U
R
A
More clues leading to the result AURA
- A biblical city with a distinctive quality
- Gold used by artist creates atmosphere
- Distinctive quality of gold shown by artist
- Distinctive quality of gold seen by painter
- Restaurant preserves distinctive character
- Gold artist used to create atmosphere
- Left-wingers in Acton unfriend rebellious, angry character
- Girl student leaves an atmosphere
- Atmosphere created by girl blowing top
- Vibes emanating from topless girl
Buddy explains!

The straight part
We know that "atmosphere" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case atmosphere = aura.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 AURA mean?
AURA noun- Distinctive atmosphere or quality associated with something.
- An invisible force surrounding a living creature.
- Perceptual disturbance experienced by some migraine sufferers before a migraine headache.
- Telltale sensation experienced by some people with epilepsy before a seizure.