INDEFINITE PRONOUM FOLLOWED BY ARTICLE?? EINEN DER
I'm trying to translate a difficult german text from late's fifties in whitch there are an indefinite pronoun followed by an article. I really don't understand when i read this. Here is the text part:
"Trozdem wäre es voreilig, deshalb von vornherein einen der Nachprüfung entzogenen Beurteilungsspielraum der Behörde zu verneinen."
Why "einen" is not followed by a substantive?? in which order should i understand it?

