The article is describing the noun, but it is placed before the adjective.
To decide between "a/an" and "the," remove the adjective or adjectives, decide which you would use with the noun, then put back the adjectives.
Can you suggest a restaurant?
Yes, I like the restaurant right across the street.
Can you suggest a good Chinese restaurant?
Yes, the little Chinese restaurant across the street is very good.
The use of "a" and "an" is strictly determined by sound, and is governed by the first sound in the word that follows it; if the word begins with a vowel, or sounds like it begins with a vowel, then "a" becomes "an."
Can you suggest a restaurant?
Can you suggest an opera?
Can you suggest a Chinese restaurant?
Can you suggest an Italian restaurant?
Can you suggest a German opera?
Can you suggest an Italian opera?
What is the Italian opera with "The Anvil Chorus" in it?