AREF is not a power supply. It is the reference voltage for the A/D converter. You are going to have to connect the DS3231 to something other than that, which will require a jumper wire.
One thing you could try (if you wish and if you're careful and at your own risk), is to bend the DS3231's Vcc pin up and then it would be easy to stick a female-male jumper wire from there to 5V.
Pete