I have the latest iOS on my iPad and iPhone with the new Music app. I speculate the Music app's cache of downloaded streaming songs is taking about 1.5 to 2.0 GB of space, which is causing both of my devices to now report "storage almost full." This will be an issue in the future when I want to add a new app to the device. How do I clear this cache?
Some details. I activated iCloud Music Library on both devices since I'm trying out Apple Music. My iPad previously had no local audio files, but a few days after activating iCloud Music Library, the "Audio" usage on the iTunes app on OSX reported about 1.5 GB. The Music app does not show up on the iPad's General>Usage>Storage page, as there is no explicitly stored music.
My iPhone on the other hand had locally stored songs. The phone reports Music app's usage as 3.0 GB, while the iTunes app on OSX reports 4.98 GB.
EDIT: Auto music downloads are disabled on both devices