The most common and most likely answer to this crossword clue is the 8 letter word VIBRATES
I've seen this crossword clue in Independent
V
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B
R
A
T
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S
Buddy explains!
The straight part
We know that "Shakes – it’s a verb" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shakes – it’s a verb = vibrates.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 VIBRATES mean?
VIBRATES verb- To shake with small, rapid movements to and fro.
- To resonate.
- To brandish; to swing to and fro.
- To mark or measure by moving to and fro.
- To affect with vibratory motion; to set in vibration.
- To please or impress someone.
- To use vibrato.