Unfortunately hard copy admits large and small secret (9)

'unfortunately' is the definition.
Both the answer and definition are adverbs.
Perhaps there's a link between them I don't understand?

'hard copy admits large and small secret' is the wordplay.
I cannot really see how this works, but
'hard' could be 'h' (abbreviation used in pencil classifications) and 'h' is located in the answer.
'large' could be 'l' (eg in clothes sizes) and 'l' is found within the answer.
'copy' could be 'ape' (ape can mean to copy or imitate) and 'ape' is present in the remaining letters.
'small' could be 's' (abbreviation - e.g. clothes size) and 's' is found in the answer.
'secret' could be 'sly' (I've seen this in other clues) and 'sly' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?