Lessons lead to more examinations (6)
I believe the answer is:
morals
'lessons' is the definition.
('moral' can be a synonym of 'lesson')
'lead to more examinations' is the wordplay.
'lead to' indicates taking the first letters.
'examinations' becomes 'orals' (oral is a kind of examination).
The first letter of 'more' is 'm'.
'm'+'orals'='MORALS'
(Other definitions for morals that I've seen before include "High principles or ethics" , "Principles based on right and wrong" , "Ethical motives" , "code?" , "Standards of behaviour" .)