Dessert course unfinished by bachelor (8)
I believe the answer is:
syllabub
'dessert' is the definition.
(syllabub is a kind of dessert)
'course unfinished by bachelor' is the wordplay.
'course' becomes 'syllabus' (academic course).
'unfinished' means to remove the last letter.
'by bachelor' becomes 'b' (abbreviation e.g. BA=Bachelor of Arts. I am not sure about the 'by' bit.).
'syllabus' with its last letter removed is 'syllabu'.
'syllabu'+'b'='SYLLABUB'
(Other definitions for syllabub that I've seen before include "Sweet creamy dessert" , "Alcohol-laced dessert" , "Traditional English dessert" , "last part of meal?" , "Buy balls (anag) - sweet" .)