Rapid writer (5)
I believe the answer is:
swift
I believe this clue is a double definition.
'rapid' is the first definition.
(I've seen this before)
'writer' is the second definition.
(Jonathan Swift, 1667-1745)
(Other definitions for swift that I've seen before include "Happening quickly; author" , "flying" , "like a peregrine falcon?" , "Quick and rapid like a long-winged bird" , "Expeditious" .)