Physically fit and strong (8)
I believe the answer is:
athletic
'physically fit and strong' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for athletic that I've seen before include "Lithe cat (anag.)" , "Sporty, able-bodied" , "Fit and sporty" , "Good at physical games" , "Active, sporty" .)