The extent to which undergraduates work (6)
I believe the answer is:
degree
'the extent' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for degree that I've seen before include "Extent of university qualification?" , "Unit of measurement of angle" , "Scholastic award for a grade on a scale" , "Unit of temperature and college award" , "Fraction of a minute" .)