Educational qualification (6)
(Other definitions for diploma that I've seen before include "Honorific document" , "Academic certificate" , "Course certificate" , "Paper showing examination success" , "Certificate awarded by college for educational attainment" .)
'educational qualification' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for degree that I've seen before include "Scholastic award for a grade on a scale" , "Not much of a turn" , "Angular unit and college award" , "Comparative amount" , "'Grade, step or award (6)'" .)