Academic errs with spoof being found out (9)
I believe the answer is:
professor
'academic' is the definition.
(professor is a kind of academic)
'errs with spoof being found out' is the wordplay.
'with' says to put letters next to each other.
'being found out' indicates anagramming the letters (discovered out of the normal letter order).
'errs' after 'spoof' is 'spooferrs'.
'spooferrs' with letters rearranged gives 'PROFESSOR'.
(Other definitions for professor that I've seen before include "University lecturer" , "One affirming faith" , "One who claims" , "One holds a chair" , "Head of faculty, department" .)