The most common and most likely answer to this crossword clue is the 5 letter word PETRA
I've seen this crossword clue in The Daily Telegraph
P
E
T
R
A
More clues leading to the result PETRA
- Ruined city's favourite artist
- Artist attached to favourite old city
- Old city type, tramp frayed at the edges
- Ancient city favoured by artist
- Old city is favourite with artist
- Upbeat areas oddly lacking in old city…
- Historic city favoured by deity
- Not all escape traders in ancient city
- Ancient city, favourite with artist
Buddy explains!

The straight part
We know that "Ancient city" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ancient city = petra.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.