The most common and most likely answer to this crossword clue is the 3 plus 3 letter word RED SEA
I've seen this crossword clue in The Daily Telegraph
R
E
D
S
E
A
More clues leading to the result RED SEA
- When swimming, reads about English stretch of water
- See doctor about a large volume of saline solution
- Body of water studied on visit, we hear
- Its partition was booked
- Ocean inlet or lake ignored by new leaders
- Body of water dried up, eastern half first
- Left wing, main site of a biblical parting gesture
- Water that separated seed sown in sun
- Scene of Biblical parting one junction away from Zhongnanhai
- I heard — looked up in the book ... see ... inlet is just south of the Sinai peninsula
Buddy explains!

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