The most common and most likely answer to this crossword clue is the 4 letter word ONYX
I've seen this crossword clue in The Times
O
N
Y
X
More clues leading to the result ONYX
- Variety of agate needs working unknown times
- Steer round extremely nasty stone
- Stone axes: small number returned [4]
- Gemstone in ring shown by New York Times
- Stone axes and miniature figure from the east
- Stone on two axes
- Stone circle shown by New York Times?
- Just left out by variety of agate
- Form of chalcedony – some chalcedony unknown
- Working factors in chalcedony
Buddy explains!

The straight part
We know that "Stone" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case stone = onyx.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 ONYX mean?
ONYX noun- A banded variety of chalcedony, a cryptocrystalline form of quartz.
- A jet-black color, named after the gemstone.
- Any of various lycaenid butterflies of the genus Horaga.
- Jet-black