Told to purchase the novel according to established rules (2,3,4)
I believe the answer is:
by the book
'established rules' is the definition.
I know nothing about this answer so I can't tell whether this works.
'told to purchase the novel' is the wordplay.
I cannot quite understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
'novel' could be 'book' and 'book' is located in the answer.
This explanation may well be incorrect...
'according to' acts as a link.
Can you help me to learn more?
(Other definitions for by the book that I've seen before include "According to the rules" , "Strictly following rules" .)