Drills and cuts round base end of pillar (9)
I believe the answer is:
exercises
'drills' is the definition.
('exercise' can be a synonym of 'drill')
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for exercises that I've seen before include "Keep-fit activities" , "Muscle movements to promote fitness" , "trains" , "Activities to develop a skill" , "Works out" .)