The most common and most likely answer to this crossword clue is the 3 letter word DEE
I've seen this crossword clue in Financial Times
D
E
E
Buddy explains!
The straight part
We know that "celebrated salmon-fishing river" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case celebrated salmon-fishing river = dee.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 DEE mean?
DEE noun- The name of the Latin-script letter D.
- Something shaped like the letter D, such as a dee lock.
- Police detective.
- To do.