Lucrative job student won't start (6)
I believe the answer is:
earner
'lucrative job' is the definition.
(I've seen this before)
'student won't start' is the wordplay.
'student' becomes 'learner' (I've seen this before).
'won't start' means to remove the first letter.
'learner' with its initial letter taken away is 'EARNER'.
(Other definitions for earner that I've seen before include "The one who brings home the money" , "Something making a good profit (colloq.)" , "Good job" , "Profitable enterprise" , "One who gets money for work" .)