The term "clean," used on the iTunes website is part of the iTunes music ratings system used to help inform parents about the nature of a song or album's musical content. Apple's iTunes adopted the term, along with others from the Recording Industry Association of America (RIAA) website and its Parental Advisory Program Summary.
The word "clean" appearing in a light grey box beside a song or album for download in the iTunes store indicates that the song or album has been edited from its original form. The cleaned version does not require a parental advisory label or warning. Songs may be free of explicit material yet not be marked clean if they didn't require editing to be considered clean.
Parental Advisory Label
The iTunes Parental Advisory label denotes possible explicit content and alerts parents that they may want to review the marked song or album for questionable content. The advisory label appears beside a song or album as the word "explicit" with a light grey box around it.
Apple's iTunes uses the Parental Advisory label in an attempt to comply with the RIAA's effort to enhance to the music industry's existing voluntary Parental Advisory Program. The program was designed to help all consumers identify sound recordings that might contain explicit lyrics. The effort is to give consumers a mechanism to monitor the content of the recordings they may want to purchase and not to create a form of censorship.