Stepping (8)
I believe the answer is:
treading
'stepping' is the definition.
('tread' can be a synonym of 'step')
This is the entire clue.
(Other definitions for treading that I've seen before include "Putting one's foot down" , "Pressing the foot down, on grapes say" , "Stepping around red giant" , "Crushing (grapes) by foot" , "walking" .)