Academic reproofs us nastily, leaving university (9)

I believe the answer is:

professor

I'm a little stuck... Click here to teach me more about this clue!

'academic' is the definition.
(I know that professor is a type of academic)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for professor that I've seen before include "Senior member of college faculty" , "University lecturer" , "One who claims" , "One affirming faith" , "Member of an academic faculty" .)

I've seen this clue in The Telegraph.

Want a hint initially instead of a full solution? Install my app