The most common and most likely answer to this crossword clue is the 7 letter word BOHEMIA
I've seen this crossword clue in The Times
B
O
H
E
M
I
A
More clues leading to the result BOHEMIA
- Snake swallowing piece representing half or quarter of artists
- Take tea crossing motorway in unconventional region
- Snake around border with India, finding ancient kingdom
- Reptile across border — one in Czech lands
- European region where half of milk goes in black tea
- Bishop with a home I rebuilt in old country
- Stink produced by man with revolutionary ambition in old kingdom
- I’m getting back into black tea, where unusual people hang out
- Czechs seen here half-eaten by snake
- Region once seeing prejudice mostly about old border
Buddy explains!

The straight part
We know that "ancient kingdom" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ancient kingdom = bohemia.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 BOHEMIA mean?
BOHEMIA noun- A community of bohemians, unconventional artists or writers.