Oleg, in English slang there is such a thing as the "A List." This means the people whose names are on it are prominent, talented, or have qualities such as that. There is also a "B List." Those whose names are on it are less prominent or talented. Of course there is no real list - it is just a slang expression. Maybe the person who wrote the phrase which contained "A Crowd" equated it with the "A List."