Test cases sorted out in class (8)
I believe the answer is:
tutorial
'class' is the definition.
(I've seen this before)
'test cases sorted out' is the wordplay.
'test' becomes 'trial' (synonyms).
'cases' is an insertion indicator (forms a case around).
'sorted' indicates an anagram.
'out' with letters rearranged gives 'uto'.
'trial' going around 'uto' is 'TUTORIAL'.
'in' is the link.
(Other definitions for tutorial that I've seen before include "Teaching session for a small number of students" , "Seminar" , "Personal teaching session" , "Session of intensive teaching to an individual or small group" , "University study period" .)