The most common and most likely answer to this crossword clue is the 8 letter word SWISHING
I've seen this crossword clue in The Times
S
W
I
S
H
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G
Buddy explains!
The straight part
We know that "Sibilant movement of air" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sibilant movement of air = swishing.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 SWISHING mean?
SWISHING verb- To make a rustling sound while moving.
- To flourish with a swishing sound.
- To flog; to lash.
- To make a successful basketball shot that does not touch the rim or backboard.
- To mince or otherwise to behave in an effeminate manner.
- (transitive) To cause a liquid to move around in a container, or in one's mouth.
- The sound of fabric or fur moving in the air.
- The movement that produces such a sound.
- A switching; a beating with twigs.
- The mutual exchange of clothes, especially at an organised party