Show me where Corbyn has said "Naz Shah is antisemitic."

He said her comments were antisemitic, and she was suspended for them.

She's apologised for her stupidity and ignorance

She apologised specifically for making antisemitic statements.

Not an official EU organisation.

The EUMC definitions are adopted by the "European Parliament Working Group On Antisemitism," are published on their website today and have been for years, and have been adopted even beyond EU.
http://www.antisem.eu/projects/eumc-working-definition-of-antisemitism/