Woman associated with garden books as part of festival (5)
I believe the answer is:
event
'part of festival' is the definition.
'woman associated with garden books' is the wordplay.
'woman associated with garden' becomes 'eve'.
'books' becomes 'nt' (New Testament).
'eve'+'nt'='EVENT'
'as' is the link.
(Other definitions for event that I've seen before include "major incident" , "A notable occurrence or happening" , "match" , "pole vault maybe" , "Occurren" .)