Right on 75% of exam - extremely confident! (5)
I believe the answer is:
exact
'right on' is the definition.
(I've seen this in another clue)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for exact that I've seen before include "correct in every detail" , "19 [WREST]" , "on the money" , "Faithful" , "Demand payment" .)