The most common and most likely answer to this crossword clue is the 5 letter word RHONE
I've seen this crossword clue in The Guardian
R
H
O
N
E
More clues leading to the result RHONE
- With new start, shone in river
- Some clear honey a flower in Europe supplied
- River, extremely rough one
- Odd heron in French river
- Royal Highness associated with a certain river
- River or bay — or at least sound
- Hard right backed by a certain French department
- Wine region right to improve
- Nothing gets one out of a river for another
- Part of greater honesty that’s starting to be seen between Swiss banks
Buddy explains!
The straight part
We know that "it ends with delta" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it ends with delta = rhone.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.