Instruction changed to ritual (8)
I believe the answer is:
tutorial
'instruction' is the definition.
(I've seen this before)
'changed to ritual' is the wordplay.
'changed' indicates anagramming the letters.
'to'+'ritual'='toritual'
'toritual' anagrammed gives 'TUTORIAL'.
(Other definitions for tutorial that I've seen before include "Period of individual instruction" , "Private lesson" , "University study period" , "Period of teaching as from college lecturer" , "A period of individual tuition" .)