how do i clean up "other" on iPad mini?

If the "other" is taking up that much space, you will have to restore to factory settings. 5.2GB of other usually means corrupted files. Restoring from backup will only bring the corrupted files back.

What is the Other on my iPhone and How to Remove It

What is "Other" and What Can I Do About It?

Use iTunes to restore your iPhone, iPad, or iPod to factory settings - Apple Support

Note: If you have a 16GB iPad, only about 11GBs are actually usable even after you restore.

See this knowledge base information about storage on an iOS device, not what is in the 'other' category. Much of the content of other cannot be removed except by erasing and restoring the device to factory condition, and then restoring the apps you need. The content of Siri voices can take space that is only available if you guit using that function.