The most common and most likely answer to this crossword clue is the 7 plus 5 plus 11 letter word CABBAGE WHITE BUTTERFLIES
I've seen this crossword clue in The Guardian
C
A
B
B
A
G
E
W
H
I
T
E
B
U
T
T
E
R
F
L
I
E
S
Buddy explains!
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.