"Pudd'nhead Wilson” author (5)
I believe the answer is:
twain
'pudd'nhead wilson author' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for twain that I've seen before include "US author Mark, attributed with the quote "golf is a good walk spoiled"" , "that was a low number" , "II?" , "two in history" , "Humorous writer - two!" .)