The most common and most likely answer to this crossword clue is the 8 letter word AIRCREWS
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More clues leading to the result AIRCREWS
Buddy explains!

The straight part
We know that "Staff on 24s" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case staff on 24s = aircrews.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 AIRCREWS mean?
AIRCREWS noun- A group of two or more trained individuals, formed as a team that operates an aircraft.