Old site set out by book is alive (8)
I believe the answer is:
existent
'alive' is the definition.
(similar in meaning)
'old site set out by book' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'set out' is an anagram indicator.
'by' says to put letters next to each other.
'book' becomes 'nt' (New Testament).
'site' is an anagram of 'iste'.
'ex'+'iste'+'nt'='EXISTENT'
'is' acts as a link.
(Other definitions for existent that I've seen before include "Having reality" , "Living" , "Actual or current, having being" .)