The most common and most likely answer to this crossword clue is the 5 plus 2 plus 5 letter word PAINT IT BLACK
I've seen this crossword clue in The Guardian
P
A
I
N
T
I
T
B
L
A
C
K
Buddy explains!
The straight part
We know that "Stones hit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case stones hit = paint it black.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.