Superior rating given to second rate books (5)
I believe the answer is:
abbot
'superior' is the definition.
(abbot is a kind of superior)
'rating given to second rate books' is the wordplay.
'rating' becomes 'ab' (both can mean a sailor).
'given to' means one lot of letters go next to another.
'second rate' becomes 'b'.
'books' becomes 'OT' (abbreviation for Old Testament).
'ab'+'b'+'ot'='ABBOT'
(Other definitions for abbot that I've seen before include "Head of a religious community" , "Supervisor of brothers" , "Convent leader, male" , "Prior's clerical superior" , "friar" .)