Round up would be better, but you need to start killing a month before seeding. Spray- wait a week, cut short with a weed whip, & remove clippings. keep the area well watered for 2 weeks to reveal any clover that survived the first spray. Apply Round up- a second time when new clover leaves appear. Wait a week , and now your ready to seed. After the lawn is established, Weed B gone can be used to control clover with out killing the grass.

If there's grass mixed in, you could use WBG CCO. If not, yep, use the Round Up.