Birthday boy in court is hard, contrary teacher (6)
I believe the answer is:
christ
'birthday boy' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'in court is hard contrary teacher' is the wordplay.
'in' indicates putting letters inside.
'court' becomes 'ct' (abbreviation used in road names).
'is hard' becomes 'h' (abbreviation used in pencil classifications).
'contrary' is a reversal indicator.
'teacher' becomes 'sir' (way of addressing a male teacher).
'sir' written backwards gives 'ris'.
'h'+'ris'='hris'
'ct' enclosing 'hris' is 'CHRIST'.
Can you help me to learn more?
(Other definitions for christ that I've seen before include "Prophet born in Bethlehem" , "Jesus" , "New Zealand city - Oxford college" .)