The most common and most likely answer to this crossword clue is the 5 plus 6 letter word SPLIT SECOND
I've seen this crossword clue in The Guardian
S
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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.
What does SPLIT SECOND mean?
SPLIT SECOND noun- The nick of time; a brief moment.