Lesson sorted out in test (8)
I believe the answer is:
tutorial
'lesson' is the definition.
(I've seen this before)
'sorted out in test' is the wordplay.
'sorted' is an anagram indicator.
'in' is an insertion indicator.
'test' becomes 'trial' (synonyms).
'out' with letters rearranged gives 'uto'.
'uto' going within 'trial' is 'TUTORIAL'.
(Other definitions for tutorial that I've seen before include "Study meeting" , "Rail tout (anag)" , "Period of teaching as from college lecturer" , "Period of individual instruction" , "Private lesson" .)