Is there?
Players have also given us strong anecdotal "evidence" that hitting is tied to eating chicken and that pitch counts don't matter. Why is there belief in clutch and stronger than anyone else's?
For that matter, the entire "clutch is not choking" argument is also probably as poorly supported. Fans like to believe in chokers, but the actual definition of one appears to be far more related to reputation than to actual performance.
Take A-Rod. He is labeled a choker because he has a reputation for not coming through in the post-season. But has he really? He has an .822OPS in the post-season. For comparison, Derek Jeter has a career .838OPS in the post-season. Yet A-Rod is the consummate choker while Jeter is considered such a post-season legend, he was nicknamed "Mr. November" for his late season clutch hits. And the difference between the two is a whoppingly negligible 0.016 OPS points?
Granted, not all post-season plate appearances are clutch situations (whatever they are), but then the post-season isn't the only time for clutch hits. It's just the most memorable one. In a very long career, Alex Rodriguez has likely had his share of successful hits in clutch situtations. But we as fans tend to give players "choke" or "clutch" reputations based on small samples and selective samples, usually spread out over multiple seasons.
Sure, a player can come through in the clutch, and a player can fail (or choke, if you prefer) in a key situation, but you really should not try to support either a key attribute of the player by citing "these are human beings" and then go on to ignore that these human beings change from year to year physically and emotionally (the typical range for sample sizes)..