The most common and most likely answer to this crossword clue is the 5 letter word ORMER
I've seen this crossword clue in Independent
O
R
M
E
R
Buddy explains!
The straight part
We know that "Seafood" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case seafood = ormer .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 ORMER mean?
ORMER noun- An abalone or sea-ear, particularly Haliotis tuberculata, common in the Channel Islands.