The most common and most likely answer to this crossword clue is the 6 letter word DELTAS
I've seen this crossword clue in Independent
D
E
L
T
A
S
More clues leading to the result DELTAS
- Alluvial deposits from lake filled round fringes
- Final sections of River Dee next to point
- Greek characters given guidance about endless assignment
- Foreign characters lasted with difficulty
- River systems approaching the sea could become salted
- Greek characters lasted poorly
- Some Greek characters lasted in translation
Buddy explains!

The straight part
We know that "Final sections of River" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case final sections of river = deltas.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.
What does DELTAS mean?
DELTAS noun- The fourth letter of the modern Greek alphabet Δ, δ.
- A landform at the mouth of a river where it empties into a body of water.
- The letter D in the ICAO spelling alphabet, which assigns words to letters of the alphabet.
- The symbol Δ.
- A small but noticeable effect. Compare epsilon.
- The set of differences between two versions of a file.
- A change in a quantity, likely from "d" for "difference".
- The angle subtended at the center of a circular arc.
- A type of cargo bike that has one wheel in front and two in back.
- The closed figure produced by connecting three coils or circuits successively, end for end, especially in a three-phase system.
- The rate of change in an option value with respect to the underlying asset's price.
- A value in delta notation indicating the relative abundances of isotopes.
- (U.S. Space Force) A military unit, nominally headed by a colonel, equivalent to a USAF operations wing, or an army regiment.