Possible Clues:

• Nix, in the Oval Office
• Overrule check on job centre
• Get the doctor around for your 34 across or put your foot down
• Power used only three times by George W. Bush
• A confused vote, altogether negative
• Don't allow to appraise the ring
• Disallow choice, two characters having switched
• See 15-Across
• Clinton denial
• Nix by Nixon, e.g.