Where E is given in senior course (6)
I believe the answer is:
afters
'course' is the definition.
(afters can mean dessert, a course of a meal)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for afters that I've seen before include "Informal desserts, puddings" , "Sweet course" , "Strafe with desserts" , "food for pudding" , "Pud" .)