Boring part in exam going over repetitive course (7)

I believe the answer is:
orbital
'going over repetitive course' is the definition.
Although both the answer and definition are adjectives, I can't understand how they can define each other.
'boring part in exam' is the wordplay.
'boring part' becomes 'bit' (both mean a piece of something. I am not sure about the 'boring' bit.).
'in' is an insertion indicator.
'exam' becomes 'oral' (spoken academic test).
'bit' going within 'oral' is 'ORBITAL'.
Can you help me to learn more?
(Other definitions for orbital that I've seen before include "Relating to a planet's or a moon's track" , "that's going around" , "Like a ring road" , "bypass" , "Of a planetary path" .)
