Prompt author (5)
I believe the answer is:
swift
This clue is a double definition.
'prompt' is the first definition.
(I've seen this before)
'author' is the second definition.
(I've seen this before)
(Other definitions for swift that I've seen before include "Fast - novelist" , "like a peregrine falcon?" , "Fast moving; bird" , "Quick Irish satirist?" , "Anglo-Irish satirist" .)