Stupidly argued with nude art student (13)
I believe the answer is:
undergraduate
'student' is the definition.
(university student)
'stupidly argued with nude art' is the wordplay.
'stupidly' indicates anagramming the letters (a stupid ordering of the letters).
'with' means one lot of letters go next to another.
'argued'+'nude'+'art'='arguednudeart'
'arguednudeart' with letters rearranged gives 'UNDERGRADUATE'.
(Other definitions for undergraduate that I've seen before include "University student yet to take degree" , "One studying for a first degree" .)