Quite a few are scratch (5)
I believe the answer is:
score
'are scratch' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for score that I've seen before include "Music from film" , "marks" , "Notch; twenty" , "Mark; twenty" , "Reckoning" .)