Cut brisket in half; rub with liquid smoke if desired, celery salt, pepper and salt. Place in a 3-quart slow cooker. Top with onion. Combine beer and Worcestershire sauce; pour over meat. Cover and cook on low for 8–9 hours or until tender.
Remove brisket and keep warm. Strain cooking juices; transfer to a small saucepan. Combine cornstarch and water until smooth; stir into juices. Bring to a boil; cook and stir for 2 minutes or until thickened. Serve beef with gravy.
* Note: This is a fresh beef brisket not corned beef.