The most common and most likely answer to this crossword clue is the 8 letter word PILCHARD
I've seen this crossword clue in The Times
P
I
L
C
H
A
R
D
More clues leading to the result PILCHARD
- Fish edge up — another fish died
- Fish in box turned stiff
- Fish cutting back, powerfully
- One with memory like a goldfish perhaps recalled excerpt with difficulty
- Cut-back that’s unfeeling
- Difficult to follow part of film about fish
- Fish and chip dish cooked with lard
- Soft, the Italian vegetable and fish
- Fish Greek character starts to cook hazardously in fat
- Sauce turning vegetable into 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 = pilchard.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 PILCHARD mean?
PILCHARD noun- Any of various small oily fish related to herrings, family Clupeidae.