Indulgent secretary leaves hard copy letter (10)
I believe the answer is:
permissive
'indulgent' is the definition.
(similar in meaning)
'hard copy letter' is the wordplay.
'hard copy' becomes 'per' (I am not sure about this - if you are sure you should believe this answer much more).
'letter' becomes 'missive' (synonyms).
'per'+'missive'='PERMISSIVE'
'secretary leaves' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
(Other definitions for permissive that I've seen before include "Liberal, broad-minded" , "Showing indulgence" , "granting authorisation" , "Lenient, indulgent" , "Free" .)