Clamp on Definition 1 of 2Pro Tip 1/3Physical Connection Refers to the physical act of fastening objects together often using a device or tool. She clamped on the broken pieces to fix the toy. Pro Tip 2/3Tight Securing Emphasizes the idea of making two things tightly secure to each other, leaving no space. To stop the leak, he quickly clamped on a seal. Pro Tip 3/3Immediate Action Often suggests an action taken quickly to prevent a problem or respond to a need. In the emergency, they clamped on a tourniquet to his leg.