Related Clues:

• One of the family assumes a right, which is questionable
• An ulcer (anag)
• Imprecise, hazy
• Nebulous nuclear fall-out
• Doubtful, pawnbroker, over a radiogram at first
• Not easy to grasp, like some physics with a bit of a twist
• Not easy to understand
• Sort of bomb with uranium going up in clouds?
• Sort of family that puts its head back in the clouds?
• Nuclear output up in the air
• Nuclear explosion not easily explained
• Relation with a right to be less than explicit
• Obscure pawnbroker turned painter
• Not certain if Sam has gone to Arabia
• Relation has a first refusal that's hard to fathom