The most common and most likely answer to this crossword clue is the 7 letter word CHICAGO
I've seen this crossword clue in The Guardian
C
H
I
C
A
G
O
More clues leading to the result CHICAGO
- Smart travel round a city
- Transatlantic city stylish in the past
- Musical regarded as elegant at one time
- Type of bridge in a pass
- US city elegantly fashionable in the past
- Port fashionable in the past
- Musical group attempt to tour America
- Down
- A city fashionable in the past
- Lake Michigan port appealingly elegant in the past
Buddy explains!

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