The most common and most likely answer to this crossword clue is the 6 letter word NAPLES
I've seen this crossword clue in The Sunday Telegraph
N
A
P
L
E
S
More clues leading to the result NAPLES
- Fellow needing sleep first in Italian port
- Planes flying somewhere in Italy
- European city that never sleeps? Not quite
- Planes travelling for city abroad
- Where you see Italians get some shut-eye … and the French
- Planes crashed in Italy
- New priest leaving fruit in Italian city
- Poles eating cored fruit in port
- Beset by scruffs, left Mediterranean city
- City sleeps around lunchtime, empty
Buddy explains!

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