Agile, sprightly (4)
I believe the answer is:
spry
I believe this is a double definition.
'agile' is the first definition.
(synonyms)
'sprightly' is the second definition.
(I've seen this before)
(Other definitions for spry that I've seen before include "Far from doddering" , "Light on one's feet" , "Quick and agile" , "Moving quickly and lightly" , "'Agile, nimble (4)'" .)