Created book without introduction; one may learn by this (4)
I believe the answer is:
rote
'one may learn by this' is the definition.
(as in learning by rote)
'created book without introduction' is the wordplay.
'created book' becomes 'wrote' (wrote a book).
'without introduction' means to remove the first letter.
'wrote' with its initial letter taken off is 'ROTE'.
(Other definitions for rote that I've seen before include "Repetition for learners" , "Repetition from memory" , "Habitual routine" , "By . . . . means by memory - that tore it" , "Mechanical routine" .)