The most common and most likely answer to this crossword clue is the 6 letter word VACANT
I've seen this crossword clue in Financial Times
V
A
C
A
N
T
More clues leading to the result VACANT
- When there's no teaching, a set of books is available
- Empty metal container covered by tax
- Empty prison covered in a TV broadcast
- Empty container dropped into large tank
- Empty one container into another
- Empty tin in tank
- Empty container covered by tax
- Empty vessel another one's filled?
- Empty container inside larger one?
- Upturned box containing a tin
Buddy explains!

The straight part
We know that "empty" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case empty = vacant.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 VACANT mean?
VACANT adjective- Not occupied; empty.
- Showing no intelligence or interest.