Witnesses going up and down (4)
I believe the answer is:
sees
I believe this is a double definition.
'witnesses' is the first definition.
('see' can be a synonym of 'witness')
'going up and down' is the second definition.
(Other definitions for sees that I've seen before include "Observes the bishops' domains" , "Watches" , "Bishops' dioceses" , "Observes or perceives" , "Dioceses; views" .)