Mojo

A mojo was among the things that Clara Oswald lost as a child. She eventually got it back. Exactly what a mojo was was not specified. (WC: The Bells of Saint John: A Prequel)

Behind the scenes
This could refer to the magazine, a music magazine that has been published in the UK since 1993.

Clara could also be using mojo as slang. To have "lost your mojo" refers to a loss of inspiration or creative genius, the loss of that special spark. Mojo can be also be a reference to charm or sex drive, a meaning heavily popularised by the  series. Since the Austin Powers films were released during Clara's childhood, she may very well have been aware of them when she made this reference.