Teacher said to go in a circle (3)
I believe the answer is:
sir
'teacher' is the definition.
(way of addressing a male teacher)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for sir that I've seen before include "address to teacher" , "Way to address gentleman" , "Polite term of address for a man" , "Respectful address for a man" , "Title for knight or teacher" .)