The most common and most likely answer to this crossword clue is the 6 letter word DURBAN
I've seen this crossword clue in The Times
D
U
R
B
A
N
More clues leading to the result DURBAN
- Diamonds from a city, a city in South Africa
- Departs from the city, one in South Africa
- Start of demolition in built-up area that is on the Indian Ocean
- Last of rand belonging to city – this one?
- Foreign port, city south of Germany
- South African city bar renovated in 2
- Departs from a city somewhere in South Africa
- Day in town or city? City
Buddy explains!

The straight part
We know that "that is on the Indian Ocean" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that is on the indian ocean = durban.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.