The most common and most likely answer to this crossword clue is the 4 letter word EBON
I've seen this crossword clue in The Times
E
B
O
N
More clues leading to the result EBON
- Poetic dark age probed by book
- Black book kept by one that's devious
- What shows black unit at last being given pride of place?
- Rare form of tree, impressive from below, dropping first of leaves
- After returning honour, name is black
- Poet’s black book one that’s devious keeps
- Black and blue bonnets, a selected series
- Black yet brown? Oddly not (4
- Dark Lord perhaps returns, crossing lake
Buddy explains!

The straight part
We know that "Black" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case black = ebon.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 EBON mean?
EBON noun- (now poetic) Ebony; an ebony tree.
- Made of ebony.
- Black in colour.