Have at least forty-one winks? (9)
I believe the answer is:
oversleep
'have' is the definition.
The answer and definition can be both related to bodily activities as well as being verbs in their base form.
Maybe there's an association between them I don't understand?
I can't explain the remainder of the clue.
(Other definitions for oversleep that I've seen before include "show signs of exhaustion?" , "Stay out too long" , "miss breakfast?" , "rest too long?" , "rest, ignoring alarm?" .)