Muscular or active (8)
I believe the answer is:
athletic
I believe this is a double definition.
'muscular' is the first definition.
(I've seen this before)
'active' is the second definition.
(similar in meaning)
(Other definitions for athletic that I've seen before include "Fit and sporty" , "Team" , "Sporty, able-bodied" , "Strong and vigorous" , "See 12" .)