the height of fashion; the cream of fashion
A somewhat literary set phrase meaning the very best or most stylish part of current fashion. Often used in commentary on clothing, design, or trends.
Her dress was the height of fashion.
This shop's selection represents the pinnacle of fashion.
Compound of 流行 (fashion, trend) + の (possessive particle) + 粋 (essence, cream). The phrase is a set expression; the exact historical derivation is uncertain.