MUSIC as displayed on the Clip (or other Sansa players) is not a folder. Music is mostly a database–EXCEPT for its Folders listing.
Music lists Artists, Albums, Songs, Genres, etc. from information gathered from the ID3 tags in the files. It finds them on both the internal memory and the card in the card slot, anywhere in folders or sub-folders, and combines them,
Folders on the display, under Music, IS a folder. It mimics a Windows folder structure, showing the two drives separately (internal and external memory) and folders and subfolders within them. If you want to use that kind of structure, just name folders and files as you want them on your computer and send them over in MSC mode (Settings/System Settings/USB Mode/MSC). But you’ll have to remember that you put Beggars Banquet in Stones and 12x5 in Rolling Stones.
You may find that the database method is more useful; it just takes a different mindset to navigate. Under Music on the display, Artists will find all your Rolling Stones songs or albums under Rolling Stones as Artist, assuming the files have good tags–that is, the Artist tag in the mp3 files says Rolling Stones, and the Album tag says Let It Bleed for every song on Let It Bleed. It will find the tags in folders named Stones, or Glimmer Twins, or Satanic Majesties, or anywhere else, assuming the ID3 tags in the files say Rolling Stones under Artist.
You can check and fix your tags–in bulk–with mp3tag, which is free.
http://www.mp3tag.de/en/
Allow it to add itself to context menus, an option while installing. Open it and go to Tools/Options/Tags/Mpeg and under Write option choose ID3v2.3 ISO-8859-1. Those are the tags that Sansa players think are extra tasty. You can, for instance, highlight all the songs on an album and tag them all “Rolling Stones” by putting that in the Artist field on the left and Save Tag.
Meanwhile, if you have files but have not filled in the tags–or got them some weird place that didn’t already have them tagged, or prefer relying on your memory about what you called any particular folder–then Folders is for you.
Sansa is one of the few players that offers that flexibility. Many players just go by the ID3 tag database.You can’t always get what you want but it’s possible you might.