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

The straight part
We know that "Vapours sprayed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vapours sprayed = aerosols.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 AEROSOLS mean?
AEROSOLS noun- A mixture of fine solid particles or liquid droplets suspended in a gaseous medium.
- An aerosol can.
- The payload (e.g. insecticide, paint, oil, cosmetics) and propellant contained by an aerosol can.
- A colloidal system in which the dispersed phase is composed of either solid or liquid particles and in which the dispersal medium is some gas, usually air.
- To spray with an aerosol.