Whacker

Example:After failing to convince the client to buy a newer car, the salesperson took out his beater and let it work its magic.

Definition:A person or thing that beats, strikes or hits something, often to achieve a result.

Example:With a hammer in one hand and a nail in another, the man became a whacker, attacking the framing with great force.

Definition:A handheld tool with a heavy head on the end of a handle, used to strike, shape, or drive in nails or other fastenings.