what does "flat clutch of the season" mean in the following passage?
From that Dutch period they might draw a line across the breastbone, revealing only upper neck and shoulders as the slender gown fell to the feet, where pads of velvet on the instep finished off the shoes.
The show opened with shorter dresses, in black and ink blue, dense lace collars giving them an ecclesiastical feel and a single plait of hair falling downward. And surely only this couple could show the flat clutch of the season and make it seem like a religious book.
(Source: The International Herald Tribune, March 7 2013, article: Stillness and grace)