"Cleaning..." phase when deleting apps
An app that shows a cleaning... label under the icon means that it is currently deleting local data such as cache and temporary files associated with the app.
This process usually takes place when your device is low in memory or just before an iCloud Backup begins. Its purpose is to free up some space.
However, I never saw this while deleting an app, it may be either a bug or a new feature that warn the user that both the app and its data is being removed from the device.
Sources : iMore, Cult Of Mac, iPhone FAQ