The most common and most likely answer to this crossword clue is the 9 letter word JITTERBUG
I've seen this crossword clue in The Times
J
I
T
T
E
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B
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G
More clues leading to the result JITTERBUG
- Flagon of beer as conveyed by Spooner to dance
- Pitcher of beer for Spooner's dance
- Nervous person lowering head of beer in beer mug
- Lively movement in Spooner’s beer glass
- Pitcher’s filled with craft bitter for dance
- Series of steps coming out of Spooner’s freezing cold prison
- Little hesitation shifting butt around in dance — this one?
- Scaremonger to skip eating refined butter
- Pitcher containing beer moving bishop to dance!
Buddy explains!

The straight part
We know that "Nervous person" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nervous person = jitterbug.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 JITTERBUG mean?
JITTERBUG noun- A one-stringed instrument (monochord) that consists of a wire string attached to something solid like the side of a house, and played with a piece of metal or glass, originating in the African American traditional music of Mississippi in the United States.
- A nervous or jittery person.
- A jazz musician or aficionado.
- An uptempo jazz or swing dance which embellishes on the two-step pattern and frequently incorporates acrobatic style swing steps.
- To dance the jitterbug.