I took apart byt brakes today and this small clip fell out from the rear inner brake pads. When I try to put it back in it barely stays there. Hard to imagine it would stay there on its own. I've tried it both upside and downside.

Does it serve some purpose? If so, Is there some trick to getting it to stay?

Thanks,

 

That appears to be the remnant of a broken or long since removed brake pad wear sensor.

 

2nd that!

Just did my MINIs brakes for the 1sr time in years and forgot how to install the inner rear brake. Quickly remembered how it just snaps onto the caliper piston.

 

That looks like the retainer for the pad wear sensor. If you don't have wear sensors, or if you have new sensors that come with new versions of this clip, you don't need it. I'm not sure that particular pad is correct for that clip on second glance.