It's just the same as what is put on disc (8)
I believe the answer is:
identity
'disc' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for identity that I've seen before include "papers" , "Absolute sameness; personality" , "Uniqueness" , "Individuality, personality" , "It's on the cards" .)