Encourage me to return book of yore (8)
I believe the answer is:
embolden
'encourage' is the definition.
(I know that embolden is a type of encourage)
'me to return book of yore' is the wordplay.
'to return' is a reversal indicator.
'book' becomes 'b' (abbreviation for book).
'of yore' becomes 'olden' (I've seen this in another clue).
'me' written backwards gives 'em'.
'em'+'b'+'olden'='EMBOLDEN'
(Other definitions for embolden that I've seen before include "Hearten" , "Inject courage into - me blonde" , "Encourage" , "Give courage to" , "Fire" .)