Possible Clues:

• Mirrored, say, in poor line of woman's gown
• Not formal address?
• Flimsy nightwear
• Female lace-trimmed garment
• Boudoir attire
• Designed, say, double line of casual dress
• Point, say, made by the foreign officer that's rejected informal attire
• A diaphanous dressing gown or nightwear garment
• Feminine at-home attire
• Elgin having lost marbles, horse half gone, revealing habit