Move unsteadily from side to side (6)
I believe the answer is:
wobble
'move unsteadily from side to side' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for wobble that I've seen before include "Move unsteadily; waver" , "Move unsteadily, quiver" , "Move unsteadily (like a jelly?)" , "Unsteady motion" , "Move unsteadily from side to side" .)