Scholarly Mike follows a scoundrel online (8)
I believe the answer is:
academic
'scholarly' is the definition.
(similar in meaning)
'mike follows a scoundrel online' is the wordplay.
'mike' becomes 'mic' (I've seen this in other clues).
'follows' says to put letters next to each other.
'scoundrel' becomes 'cad' (cad is a kind of scoundrel).
'online' becomes 'e' (abbreviation for electronic, e.g. in ecommerce).
'a'+'cad'+'e'='acade'
'mic' after 'acade' is 'ACADEMIC'.
(Other definitions for academic that I've seen before include "Scholarly as opposed to practical (8)" , "of educational kind" , "Scholarly; irrelevant" , "Scholastic" , "Intellectual" .)