Adding 1 song to wishlist

I am having the same issue. I went to Apple support and I typed in "How to use wish list" and at the very bottom under GOOD TO KNOW it says "On iOS 7, you can't add individual tracks to your Wish List, only albums."

If you log into your iTunes account on a PC or mac, you will be able to add single songs to the Wishlist.

On you iTune, click on the arrow button right next to the price of the song, the drop down menu should appear and there is an option to 'add to wish list'. Hope this helps.