He wrote Book Two (4,5)
I believe the answer is:
mark twain
'he wrote' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'book two' is the wordplay.
'book' becomes 'mark' (book of the Bible).
'two' becomes 'twain' (archaic term for 'two').
'mark'+'twain'='MARK TWAIN'
Can you help me to learn more?
(Other definitions for mark twain that I've seen before include "US writer" , "Creator of Tom Sawyer and Huckleberry Finn" , "Tom had him writing about?" , ""The Adventures of Huckleberry Finn" author" , "Writer of Huckleberry Finn" .)