A clutch bag is a small handbag without handles or a strap, held in the hand, tucked under the arm, or 'clutched' against the body — hence the name. Clutches are traditionally evening bags, designed for occasions where you need to carry minimal essentials: phone, cards, lipstick, keys.
The category ranges from soft envelope clutches to rigid minaudières (structured clutches, often with a decorative clasp). Chanel's Boy Brick and Jimmy Choo's Jay clutch are examples at the luxury end. Soft leather clutches work equally well for day or night.
Clutch vs. Pouch
A pouch is a soft, often unstructured small bag — typically without hardware — that can be carried as a clutch or zipped inside a larger bag as an organiser. Pouches are more casual; a clutch implies evening or occasion dressing. The Louis Vuitton Pochette Accessoires is technically a pouch that's frequently carried as a clutch.