The most common and most likely answer to this crossword clue is the 7 letter word SOCKEYE
I've seen this crossword clue in Financial Times
S
O
C
K
E
Y
E
Buddy explains!

The straight part
We know that "salmon" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case salmon = sockeye.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 SOCKEYE mean?
SOCKEYE noun- A small salmon with red flesh, Oncorhynchus nerka, found in the coastal waters of the northern Pacific.
- The edible flesh of this fish.