Cancel article omitted from yearbook (5)
I believe the answer is:
annul
'cancel' is the definition.
(I know that annul is a more specific form of cancel)
'article omitted from yearbook' is the wordplay.
I cannot really understand how this works, but
'article' could be 'an' (English indefinite article) and 'an' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for annul that I've seen before include "Obligation" , "Cancel officially" , "Declare void" , "Recall" , "Cancel, say a law" .)