Quick to knock with papers (5)
I believe the answer is:
rapid
'quick' is the definition.
('rapid' can be a synonym of 'quick')
'knock with papers' is the wordplay.
'knock' becomes 'rap' ('rap' can be a synonym of 'knock').
'with' means one lot of letters go next to another.
'papers' becomes 'id' (identification papers).
'rap'+'id'='RAPID'
'to' is the link.
(Other definitions for rapid that I've seen before include "Fast, quick" , "Fast, speedy" , "Flying" , "Electrical connector" , "haste" .)