The most common and most likely answer to this crossword clue is the 7 letter word YANGTZE
I've seen this crossword clue in The Guardian
Y
A
N
G
T
Z
E
More clues leading to the result YANGTZE
- Get any in arrangement with Zulu banker?
- Get kicks with zany foreign banker
- Any degenerates get involved with Zulu banker?
- Ending in custody, agent touring around unknown river
- At first you’re all nervous, giving the Zulu elder a flower
- River voyage danger? Ditch dozens in the centre
- Get drunk with zany banker
- Great flower in manly nature article, unknown for its heart
- Two unknowns penning article on great European river
- Suspect unknown double agent as long-distance runner
Buddy explains!

The straight part
We know that "river" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case river = yangtze.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.