Small tear or cut in leather?

"Elmer's Glue". It works.

Also Super Glue, but you risk sticking your finger to the surface when you press it down.

do you put a patch behind the tear first? thanks

No, but this is more of a tear or cut, but not cut all the way through. If you have a separation cut in the leather, you need a pro to patch that and re-bond it.