Mark scored? That may go up or down (5)
I believe the answer is:
minim
'up or down' is the definition.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for minim that I've seen before include "Short note" , "Double crotchet" , "Quarter of a breve" , "note or > dose" , "Note with value of half a semibreve" .)