Unorthodox book (5)
I believe the answer is:
novel
This clue might be a double definition.
'unorthodox' is the first definition.
Both the answer and definition are adjectives. Maybe you can see a link between them that I don't see?
'book' is the second definition.
(novel is a kind of book)
Can you help me to learn more?
(Other definitions for novel that I've seen before include "New piece of fiction?" , "Innovative" , "story" , "Kim, eg" , "work of Dickens?" .)