Studious learner involved in editing novel (8)
I believe the answer is:
diligent
'studious' is the definition.
('diligent' can be similar in meaning to 'studious')
'learner involved in editing novel' is the wordplay.
'learner' becomes 'l'.
'involved in' is an insertion indicator.
'novel' indicates an anagram.
'editing' is an anagram of 'diigent'.
'l' placed into 'diigent' is 'DILIGENT'.
(Other definitions for diligent that I've seen before include "Steady in application and industry" , "Steady and hard-working" , "Working hard and conscientiously" , "Assiduous" , "Showing care and effort" .)