The most common and most likely answer to this crossword clue is the 7 plus 3 plus 6 letter word ORANGES AND LEMONS
I've seen this crossword clue in The Guardian
O
R
A
N
G
E
S
A
N
D
L
E
M
O
N
S
Buddy explains!
The straight part
We know that "fruit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fruit = oranges and lemons.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.