be (as) clean as a whistle

be (as) clean as a whistle

1. To be neat and tidy in appearance. This house needs to be as clean as a whistle before my mother-in-law gets here.
2. To be well-behaved and not involved in illegal or questionable activities. You can trust George, he's a good kid—as clean as a whistle. I don't have a criminal record, I'm clean as a whistle.
See also: clean, whistle