Cancel article omitted from yearbook (5)
I believe the answer is:
annul
'cancel' is the definition.
(annulling is a kind of cancelling)
'article omitted from yearbook' is the wordplay.
I cannot quite understand how this works, but
'article' could be 'an' (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" .)