The most common and most likely answer to this crossword clue is the 6 letter word WRITHE
I've seen this crossword clue in The Guardian
W
R
I
T
H
E
More clues leading to the result WRITHE
- Summons he delivered, making us squirm
- Produce book, penning ultimate in ghoulish twist
- Horse getting into pen to roll around on ground
- Twist and turn to set down outside hotel
- Decline, as partner finally rises to do the twist?
- Squirm where governor served with court order
- . Legal document getting that chap to squirm
- Thrash youth’s backside in pen
- Summons male to move sinuously
- Legal document with explosive twist
Buddy explains!

The straight part
We know that "to move sinuously" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to move sinuously = writhe.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 WRITHE mean?
WRITHE noun- A contortion.
- (knot theory) The number of negative crossings subtracted from the number of positive crossings in a knot
- To twist, to wring (something).
- To contort (a part of the body).
- To twist or contort the body; to be distorted.
- To extort.