Way to address schoolmaster in class, I reckon (3)
I believe the answer is:
sir
'way to address schoolmaster' is the definition.
I can't tell whether this definition defines the answer.
'in class i reckon' is the wordplay.
'in' says the answer is hidden in the clue.
'SIR' is hidden within 'class i reckon'.
Can you help me to learn more?
(Other definitions for sir that I've seen before include "as Winston Churchill was" , "Title for knight or teacher" , "Respectful address for a man" , "Title of 1 across" , "Baronet's title" .)