The most common and most likely answer to this crossword clue is the 6 plus 3 letter word IONIAN SEA
I've seen this crossword clue in The Daily Telegraph
I
O
N
I
A
N
S
E
A
More clues leading to the result IONIAN SEA
- Drink one in Asia? Wrong
- Part of Mediterranean island? One’s in a developed area
- One working with Asian swimming across eastern part of Mediterranean
- Area of the Med — one in Asia being developed
- Scottish island engages native perhaps draining sewage in mass of water
- A noise in a swirling expanse of water
- Marine area — one in Asia to be developed
- Part of Mediterranean island? One's in a developed area
Buddy explains!
The straight part
We know that "expanse of water" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case expanse of water = ionian sea.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.