The most common and most likely answer to this crossword clue is the 7 letter word ARUNDEL
I've seen this crossword clue in Financial Times
A
R
U
N
D
E
L
More clues leading to the result ARUNDEL
- Castle requiring a single key
- Rue land being redeveloped in Sussex town
- Part of 10‘s a circular, slightly elliptical line – no circle
- Sussex town seminar – undelivered packages
- Deal set out about marathon, possibly, in Sussex town?
- English town where Under-ground is taken by almost all
- Deal devised about series in Sussex town
Buddy explains!
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.