About to absorb old books as a way to learn (4)
I believe the answer is:
rote
'a way to learn' is the definition.
(as in learning by rote)
'about to absorb old books' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'to absorb' indicates putting letters inside.
'old books' becomes 'OT' (Old Testament).
're' placed around 'ot' is 'ROTE'.
'as' is the link.
(Other definitions for rote that I've seen before include "Unthinking repetition" , "By . . . . - from memory without thought" , "Repetition from memory" , "performance based solely on routine" , "Repetition for learners" .)