Making a character clap

There is no way to have normal hands (attached to arms and body etc) collide. So you cannot just throw the hands together and have them stop.

Instead, you can do things like add a second dragger behavior to the puppet then record one hand with the first dragger, then record the second hand using the second dragger. This will show you where the hand Other hand is while recording. Then just keep retrying until it looks good (can be painful!)

You can also do single frame recordings to get more control.  Record a series of single frames in new positions.

There are other tricks. You can create another set of arms (using a swapset) then add a Transform behavior to the hand instead of a dragger. (You cannot have both at the same time.) You can then record a new X/Y value for the hand (to exactly position them next to each other) and use blends to smoothly transition the hands tonwards each other and back again. If you go this route I can point you at more examples of precise movements with blends. This might help https://extra-ordinary.tv/2018/08/08/timing-music-with-character-animator-movements/