Sprightliness (7)
I believe the answer is:
agility
'sprightliness' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for agility that I've seen before include "dexterity" , "Physical ability to move nimbly and quickly" , "Spryness" , "Physical nimbleness, easy movement" , "Sprightliness" .)