Hi,
With this setup the whole current clamp is almost floating, thus picking up any noise around.
Better do it the other way round:
GND - [clamp_minus - clamp_plus] - capacitor - voltage divider (470k to GND, 470k to VCC) and ADC.
For low power you usually an the voltage at the pins either close to GND or close to VCC.
So if you switch the pin to OUT, LOW then it should be fine. But it draws 470k @5V in the voltage divider.
Mind that it needs some time to settle to VCC/2 after power down.
Klaus