Unprecedented work of fiction (5)
I believe the answer is:
novel
This clue is a triple definition!
'unprecedented' is the first definition.
(I've seen this in another clue)
'work' is the second definition.
(type of literary work)
'of' acts as a link.
'fiction' is the third definition.
(novel is a kind of fiction)
(Other definitions for novel that I've seen before include "Scoop, say" , "A work of fiction of new kind" , "Romance - new" , "New and strange" , "Book of prose fiction" .)