I came upon a sentence I can’t grasp in a text book.
The sentence is the following
What so often happens is that either that day or over time, less and less is kept, first of winnings and then of the sum originally slated for wagering.
I know that an inversion is used in a subordinate clause. So the subject is “first of Winnings and then of the sum originally slated for wagering”.
Here I can’t understand the phrase “then of”
I think the part of speech of “then” might be an adjective. Is it possible that part of the subject is an adjective in the sentence.