Clean room to keep you sharp across finals (3,2)
I believe the answer is:
mop up
'clean' is the definition.
(to mop something up is to clean it)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for mop up that I've seen before include "Kill (enemy stragglers)" , "Complete final stage (of a task)" , "polish off" , "take care of" , "Clear away, dispose of" .)