Invalidate yearbook removing second article (5)
I believe the answer is:
'invalidate' is the definition.
(I know that invalidate can be written as annul)
'yearbook removing second article' is the wordplay.
I cannot really 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 "Countermand" , "Declare void" , "Make invalid" , "Cancel officially" , "Scrap" .)