"Explicit tracks" are disabled in iTunes Radio by default. To allow explicit content on iTunes Radio, open your Music app and tap the iTunes Radio tab. Next, select any iTunes Radio station from the available options, and tap the "i" in a circle at the top of the screen to open the options menu. Scroll down until you see "Allow Explicit Tracks" and tap the slider until it turns green. This will allow you to listen to explicit tracks on all iTunes Radio stations.
How do I disable / enable explicit content on iTunes Radio?
Taxonomy upgrade extras: