Op amp zener clamp design
1 - If you're going to use +/- 7 volt supplies, and you want to limit the ADC input to +/- 7 volts, why bother with all this stuff? Make a simple follower with (let's say) a 1k input resistor, as you have shown. With +/- 7 volts on the op amp, you cannot put out more than +/- 7 volts. If you're worried about high input voltages brute-forcing through the op amp, use a divide by two voltage divider and a x2 amplifier setup, like 







simulate this circuit &ndash; Schematic created using CircuitLab

2 - Why do you think that a +/- 7 volt supply will let the 5532 put out +/- 7 volts? This ability would make the 5532 a RRO (rail-to-rail output) op amp, and it most assuredly is not. If you look at the data sheet you'll see that, for +/- 15 volt input, the ouput swing (Vopp) is only guaranteed to be about 24 volts, with 26 as typical. This suggests that the output will only swing to within about 2 volts of the supplies, which would give you +/- 5 volts. You really need to be careful in trying to estimate this, since the figure is not specified for other supply voltages. Experimentation is definitely called for.