The most common and most likely answer to this crossword clue is the 4 letter word FUGU
I've seen this crossword clue in The Times
F
U
G
U
More clues leading to the result FUGU
Buddy explains!

The straight part
We know that "Delicacy of Japanese" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case delicacy of japanese = fugu.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 FUGU mean?
FUGU noun- Blowfish: a delicacy popular in Japan served raw as sushi that may, if improperly prepared, contain deadly levels of neurotoxins.