Verbal lesson initially lost (4)
I believe the answer is:
oral
'verbal' is the definition.
(I've seen this before)
'lesson initially lost' is the wordplay.
'lesson' becomes 'moral' (as in the moral of the story).
'initially lost' means to remove the first letter.
'moral' with its first letter removed is 'ORAL'.
(Other definitions for oral that I've seen before include "Relating to speech" , "Spoken exam" , "By word of mouth, like some exams" , "Type of exam" , "By word of mouth, say exam" .)