Expert wrongly faults me over one of the three R’s (9)
I believe the answer is:
masterful
'expert' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for masterful that I've seen before include "Dominant" , "Having dominating quality" , "overbearing" , "Domineering" , "expert" .)