Loathe getting low grades on exam (6)
I believe the answer is:
detest
'loathe' is the definition.
(I've seen this before)
'low grades on exam' is the wordplay.
'low grades' becomes 'de' (I've seen this in other clues).
'on' says to put letters next to each other.
'exam' becomes 'test' (synonyms).
'de'+'test'='DETEST'
'getting' acts as a link.
(Other definitions for detest that I've seen before include "Really dislike" , "Be unable to stand" , "Abominate" , "Deplore" , "Find repulsive" .)