Book published every year (6)
I believe the answer is:
'book published every year' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for annual that I've seen before include "Type of year book" , "Once a year, perhaps a book" , "Hardy it may be" , "(Of plant) living for a year or less" , "Plant that lives and dies within one year" .)