Move in waves (8)
I believe the answer is:
undulate
'move in waves' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for undulate that I've seen before include "Move with a wave-like motion" , "Rise and fall like waves" , "Go gently up and down" , "Move with a rising and falling motion" , "Move like waves" .)