Book for a series? (5)
I believe the answer is:
order
This clue is a double definition.
'book' is the first definition.
(order book is a kind of book)
'series?' is the second definition.
(series is a kind of order)
'for a' acts as a link.
(Other definitions for order that I've seen before include "Direct - sequence" , "Instruct" , "Uniformity or fraternity" , "One may be tall if demanding" , "eg OBE" .)