Penning article, cancel dated book (6)
I believe the answer is:
annual
'book' is the definition.
(annual is a kind of book)
'penning article cancel dated' is the wordplay.
I cannot quite understand how this works, but
'article' could be 'an' (English indefinite article) and 'an' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for annual that I've seen before include "Yearly publication" , "Every twelve months" , "(Of plant) living for a year or less" , "Coming once a year" , "Plant that lives and dies within one year" .)