Plan one good book to conclusion (6)
I believe the answer is:
intend
'plan' is the definition.
(I know that plan is a more specific form of intend)
'one good book to conclusion' is the wordplay.
'one' becomes 'i' (Roman numeral).
'good book' becomes 'NT' (New Testament).
'to conclusion' becomes 'end' (something's conclusion is its end).
'i'+'nt'+'end'='INTEND'
(Other definitions for intend that I've seen before include "Have as purpose or plan" , "Have as one's plan" , "Mean; aim" , "Signify" , "Mean (to do something)" .)