Do some last-minute studying (4)
I believe the answer is:
cram
'do some last-minute studying' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cram that I've seen before include "Study intensively" , "Crowd or pack to capacity" , "Swot (for exam)" , "Stuff; study hard" , "Pack in or study hard" .)