Book house overlooking ocean (5)
I believe the answer is:
hosea
'book' is the definition.
(book of the Hebrew Bible)
'house overlooking ocean' is the wordplay.
'house' becomes 'ho' (abbreviation for house).
'overlooking' is a charade indicator (letters next to each other) (down clues only).
'ocean' becomes 'sea' ('sea' can be a synonym of 'ocean').
'ho'+'sea'='HOSEA'
(Other definitions for hosea that I've seen before include "OT prophet" , "bookmaker" , "Book writer" , "Book of the Old Testament - a shoe (anag)" , "Book of prophecies" .)