The most common and most likely answer to this crossword clue is the 6 plus 4 plus 5 plus 1 plus 15 letter word BURTON UPON TRENT > BENNNOOPRRTTTUU
I've seen this crossword clue in The Guardian
B
U
R
T
O
N
U
P
O
N
T
R
E
N
T
>
B
E
N
N
N
O
O
P
R
R
T
T
T
U
U
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.