Move smoothly (6)
'move smoothly' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for glide that I've seen before include "Skim" , "Slide smoothly" , "Move smoothly along a surface" , "Fly through the air with the greatest of ease" , "Move smoothly, as a sailplane" .)
(Other definitions for glides that I've seen before include "Moves along smoothly as on skates" , "Moves smoothly over surface" , "Flies without power" , "Sails or floats on high" , "Flies without an engine" .)