Pièce métallique qui retient, assujettit. A piece of metal that holds or fastens. A fastener. A kind of staple.
These are the fasteners that hold vines to their support wires. The vineyard workers go through and carefully attach the vines in spring and summer, and then in autumn and winter they go back and remove all the wire fasteners before they prune the vines. Fasteners. Fastidious. Not fast work.