Pilgrim's Progress author (6)
I believe the answer is:
bunyan
'pilgrim's progress author' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for bunyan that I've seen before include "Writer" , "Paul -, US mythic hero" , "John . . . . . . wrote 'The Pilgrim's Progress'" , "The Pilgrim's Progress author, d. 1688" , "author John" .)