I mark zero incorrect in pile of papers (5)
I believe the answer is:
inbox
'i mark zero incorrect' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'in pile of papers' is the wordplay.
'pile of papers' becomes 'box' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in'+'box'='INBOX'
Can you help me to learn more?
(Other definitions for inbox that I've seen before include "Folder receiving emails" , "Email folder" , "file" .)