The most common and most likely answer to this crossword clue is the 7 letter word GRAVLAX
I've seen this crossword clue in The Guardian
G
R
A
V
L
A
X
More clues leading to the result GRAVLAX
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 = gravlax.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 GRAVLAX mean?
GRAVLAX noun- Salmon dry-cured in salt, seasoned with dill and sugar, and served usually thinly sliced as an appetizer.