The most common and most likely answer to this crossword clue is the 6 plus 3 plus 6 letter word ACROSS THE STREET
I've seen this crossword clue in The Guardian
A
C
R
O
S
S
T
H
E
S
T
R
E
E
T
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.