Anti-Deathclaw tactics are summed up as: Dart Gun, then Flamer. At least for me and my big guns. Something else that works is mines, then a powerful assault weapon. An alternative is a highly specialized Melee build and Jack, but that's for courageous folks only.
Deathclaws are also like any other monster: You shoot them enough, and they will die. Make sure you're using your second-best weapon if the Fat Man is in your inventory, and that you've got plenty of points(At least 80) in whatever skill this weapon uses.
But you're playing Broken Steel, and you're level 14 and trying to take on Deathclaws? The best advice I can give you is...walk away. Go perform some side quests, hunt some Enclave, level up a bit and come back and make those Deathclaws your [censored] when you're a little more powerful and better equipped. Lvl 20 should be enough.
-Nukeknockout