Able to move quickly and easily (5)
I believe the answer is:
agile
'able to move quickly and easily' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for agile that I've seen before include "Nimble, quick-moving" , "Quick in movement" , "Sprightly" , "Quick and easy-moving" , "Nimble, fleet" .)