Professor is a scoundrel with mutant mice (8)
I believe the answer is:
academic
'professor' is the definition.
(I know that academic is a type of professor)
'a scoundrel with mutant mice' is the wordplay.
'scoundrel' becomes 'cad' (cad is a kind of scoundrel).
'with' is a charade indicator (letters next to each other).
'mutant' indicates anagramming the letters.
'mice' with letters rearranged gives 'emic'.
'a'+'cad'+'emic'='ACADEMIC'
'is' is the link.
(Other definitions for academic that I've seen before include "Professor possibly" , "Of purely theoretical interest" , "A person studying" , "Scholarly (person)" , "Donnish" .)