Plumbing connections for water.

I've seen some PEX crimping tools which have a cutting blade. In theory, if the tool was there to cut the clamp, it can go back in to crimp it... but one might have better luck with a cordless Dremel to grind off the crimped part, pop the ring off, then replace it with a stainless steel band, or if one is replacing a cracked fitting, perhaps use a Flair-It fitting.

I've read good things about the Flair-It fittings. No tools needed, and I've yet to read a complaint about leaks, which says something.