The following is from NY Times.
"The decline is the result of the rise of untraditional business structure, the effects of a more globalized economy, and a labyrinth of subsidies and tax credits."
In the sentence above, the indefinite article "a" is used before "labyrinth". I understand that a definite article is used before a noun when the noun is restricted by an of-phrase, so becomes identifiable. But my question is, what does it exactly mean to restrict a noun? I can see that "effects" from the sentence is clearly restricted by "a more globalized economy". Then, is the reason "a" is used before "labyrinth" instead of "the" is that because "subsidies and tax credits" do not restrict the word labyrinth like "a more globalized economy" does "effects" and they just show some characteristics that "labyrinth" has?