The most common and most likely answer to this crossword clue is the 5 letter word TROUT
I've seen this crossword clue in The Times
T
R
O
U
T
More clues leading to the result TROUT
- Racecourse spy eating river fish
- Racehorse spy eating river fish
- Political extremist sheltering union leader? Something fishy here
- Sailor losing heart, away getting fish
- Swimmer, for all to see, clad in red
- Ultimately, meat beat fish
- Fish from river seized by hawk
- Hawk grabs river fish
- Famous quintet finally meet defeat
- French all lining river to get fish
Buddy explains!

The straight part
We know that "fish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fish = trout.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 TROUT mean?
TROUT noun- Any of several species of fish in Salmonidae, closely related to salmon, and distinguished by spawning more than once.
- An objectionable elderly woman.
- To (figuratively) slap someone with a slimy, stinky, wet trout; to admonish jocularly.