Apparatus and methods for clamping and controlling flash around a manufacturing tool engaging a workpiece and preventing fill within the workpiece. In one embodiment, a clamp for securing a workpiece during a manufacturing operation includes a housing and a foot biased away from the housing, the foot defining an opening through which a manufacturing tool may pass to engage the workpiece. In another embodiment, the manufacturing tool is a rotating or counter-rotating shoulder friction stir spot welding tool. In accordance with other aspects of the invention, the foot defines at least one recess for holding flashing.