Recommended for New Designs
The ADP5073 is a high performance dc-to-dc inverting regulator used to generate negative supply rails.
The input voltage range of 2.85 V to 15 V supports...
ADP5073 on Analog.com
What will the efficiency be when Vin=3.3, Vout=-3.3V, Iout=1A?
You need ADP5074 to get higher output current. Even then, ADP5074 at your input and output voltages can only provide up to around 0.8A. At 0.8A, efficiency will be about 72%.
Is there a higher efficiency part, which can provide -3.3V and 1A out with 3.3V+-5% in?
Please check these parts. You can use LTpowerCAD