I know people who do clip their rat's claws, but it is not easy if the rat isn't into it! You can tell where to clip because thier nails are clear, don't clip into the red/pink area, just nip the tip, you can get tiny nail clipper sicssors from the pet store that are used for birds and reptiles. An alternative to cliping is to take a nail file and gently run their nails across it, this will take off that sharp point without having to actually clip.

Cheers,
Tigeress