The most common and most likely answer to this crossword clue is the 8 letter word INHALERS
I've seen this crossword clue in The Times
I
N
H
A
L
E
R
S
Buddy explains!

The straight part
We know that "Vapers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vapers = inhalers.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 INHALERS mean?
INHALERS noun- One who inhales.
- A device with a canister holding medicine (either in powder or gas form) which is sprayed and inhaled by the patient, often for treating asthma and other respiratory diseases.