Learners in capers collecting low grades (8)
I believe the answer is:
students
'learners' is the definition.
(student is a kind of learner)
'capers collecting low grades' is the wordplay.
'capers' becomes 'stunts' (I've seen this in another clue).
'collecting' means one lot of letters goes inside another.
'low grades' becomes 'de' (D and E are low academic grades).
'stunts' enclosing 'de' is 'STUDENTS'.
'in' acts as a link.
(Other definitions for students that I've seen before include "Eg, undergraduates" , "Sent dust to those who learn" , "Pupils at school, university etc" , "Learners as at school" , "Pupils, learners" .)