Speaking, go over and over part (4)
I believe the answer is:
role
'part' is the definition.
('role' can be a synonym of 'part')
'speaking go over and over' is the wordplay.
'speaking' shows a homophone (sound like).
'go over and over' becomes 'roll' (I've seen this before).
'roll' is a homophone of 'ROLE'.
(Other definitions for role that I've seen before include "Part played (in life?)" , "Function; part" , "Part in play, film etc" , "Part (in drama)" , "Character" .)