Quick answer: clean is a neutral motion with the arms held straight down at the sides, fists lightly closed - used as a reset position between other, more distinct motions.
What Does It Look Like?
Both arms hang straight down at the sides of the body, close to the legs, with hands in a light fist, and the body held upright and still.
How the Term Is Used
"Clean" is used both as the name of this specific neutral position and, more broadly, as a general term for sharp, precise motion technique - a team is described as "clean" when their motions are well-matched and controlled.
Where It Fits in a Routine
The clean position is commonly used as a starting or resetting position between chants, dances or motion sequences, giving the team a clear, matching baseline to snap out of.
What Judges Look For
Judges are generally looking for stillness and consistency in the clean position - no fidgeting or mismatched arm placement - since it's often the position a team is judged from at the very start of a section.
Related Motions
Clean is closely related to the clasp as another neutral reset position, and contrasts with fully extended motions such as the low V.