Vigorous, active (9)
I believe the answer is:
energetic
I believe this is a double definition.
'vigorous' is the first definition.
(similar in meaning)
'active' is the second definition.
(associated in meaning)
(Other definitions for energetic that I've seen before include "High-powered" , "'Animated, full of life (9)'" , "Forceful, vigorous" , "Full of go" , "Brisk" .)