According to UrbanDictionary.com, the word "Clutch" can be defined as follows:
To me, however, CLUTCH simply refers to one of the very best rock bands that you'll ever see or hear.
I saw these guys playing live several years ago, I think they might have been opening for the one and only MOTORHEAD (RIP Lemmy). They killed it that night.
I'm not actually a big fan of their music, though. I listen to CLUTCH occasionally because, well, they're awesome. But I'm not nearly as into them as a couple of my friends are; like, say, MASTODON, they are something of an acquired taste.
That being said... it's hard to argue with their ability to lay down some amazing grooves.