Does clutch exist in other sports?
If you define clutch as the ability not to choke under pressure, than I can agree that clutch exists, even in baseball. In that case, however, I would consider pretty much all MLBers as being clutch, as I've said before.
If you define clutch as the ability to raise one's performance/ability to a level where it normally isn't, then I do not think it exists. Yes, one can have a clutch moment, but it is not a repeatable skill.
In terms of the young kid making the free throws, he absolutely gets credit for not choking under pressure. But did he raise his ability to a whole new level in that moment? I don't think so.
I honestly don't know what kind of research has been done on clutch in other sports, but it would be interesting to know what their findings are, if the research does indeed exist.