Book after Song of Solomon (6)
I believe the answer is:
isaiah
'book after song of solomon' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for isaiah that I've seen before include "Major Hebrew prophet and O.T. Book" , "Book and prophet of the Old Testament" , "Book of prophecies in the Bible" , "8th century Hebrew prophet and O.T. Book" , "Sir - Berlin, twentieth century political historian" .)