The most common and most likely answer to this crossword clue is the 6 plus 8 letter word TARGET PRACTICE
I've seen this crossword clue in The Guardian
T
A
R
G
E
T
P
R
A
C
T
I
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E
More clues leading to the result TARGET PRACTICE
Buddy explains!
The straight part
We know that "when shots may go astray" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case when shots may go astray = target practice.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.