The most common and most likely answer to this crossword clue is the 7 letter word BELFAST
I've seen this crossword clue in The Guardian
B
E
L
F
A
S
T
More clues leading to the result BELFAST
- Clanger: left out large fixed capital
- Swine has large following in capital
- Rocky tables bearing fine port
- Don’t dilly-dally crossing line in city in UK
- Capital is firm following endless alarm
- Live with large fleet where 28 came from
- Sporting legend admitted learning football artistry originally here
- Sing out, holding scale notes in European city
- Heads of local football association hosted by an icon of Manchester City
- Capital is strong following detailed warning
Buddy explains!

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