Books, or book dropped into surrounding water — from this? (9)
I believe the answer is:
motorboat
'this?' is the definition.
The definition suggests a singular noun which matches the answer.
'books or book dropped into surrounding water' is the wordplay.
'books' becomes 'OT' (abbreviation for Old Testament).
'book' becomes 'b' (abbreviation for book).
'dropped into' is an insertion indicator.
'surrounding water' becomes 'moat' (water surrounding a castle).
'ot'+'or'+'b'='otorb'
'otorb' going within 'moat' is 'MOTORBOAT'.
'from' is the link.
(Another definition for motorboat that I've seen is " powered vessel".)