Drill; activity (8)
I believe the answer is:
exercise
This clue is a double definition.
'drill' is the first definition.
(I know that drill can be written as exercise)
'activity' is the second definition.
(I know that exercise is a type of activity)
(Other definitions for exercise that I've seen before include "Do it to get fit" , "problem" , "Physical exertion for keeping fit" , "Practice session" , "Exertion to develop fitness" .)