Good times and bad, one can always count on Oscar de la Renta to deliver real clothes, the kind that have at least a prayer of being purchased and worn. He did just that in his pre-fall show on Monday afternoon, with a focus on snappy tweeds, their appealing young spirit punctuated with cute, runway-only knee socks. Another terrific motif: the textured knits. By de la Renta’s standards, this was a quiet affair as befits the times, though he did indulge in a feathered finale. While the first such look, a plumed skirt and cashmere sweater, felt jarring, three short party frocks into the motif, de la Renta at least scored points for optimism.