Free Latin book a Greek character returned (8)
I believe the answer is:
liberate
'free' is the definition.
(liberating is a kind of freeing)
'latin book a greek character returned' is the wordplay.
'latin book' becomes 'liber' ('book' in Latin).
'a greek character' becomes 'eta' (letter from the Greek alphabet).
'returned' says the letters should be written in reverse.
'eta' back-to-front is 'ate'.
'liber'+'ate'='LIBERATE'
(Other definitions for liberate that I've seen before include "Free (someone)" , "Set free, as from oppressive authority" , "Set free, emancipate" , "let go" , "Deliver" .)