One may do this after an alarming breakdown (9)
I believe the answer is:
oversleep
'one may do' is the definition.
The definition and answer can be both related to bodily activities as well as being verbs in their base form.
Perhaps there's an association between them I don't understand?
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for oversleep that I've seen before include "show signs of exhaustion?" , "Stay out too long" , "start being late?" , "not be able to get up" , "rest, ignoring alarm?" .)