Study at the last minute (4)
I believe the answer is:
cram
'study at the last minute' 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 "Stuff (facts for exam)" , "Swot (for exam)" , "Study hard for exam" , "Revise hard" , "Pack in or study hard" .)