The most common and most likely answer to this crossword clue is the 4 plus 6 letter word DILL PICKLE
I've seen this crossword clue in Financial Times
D
I
L
L
P
I
C
K
L
E
Buddy explains!
The straight part
We know that "Preserved cucumber" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case preserved cucumber = dill pickle.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.