Yes, probably for now. The heating power will be lower but you will have the confidence of sufficient current capacity while you're checking that the iron itself is ok.
Ultimately I would aim for a reliable, ie, genuine laptop manufacturer, PSU for it. Don't forget to go for a 3 pin mains input one to ensure that it's output is grounded rather than being subject to Y-cap leakage. I know Lenovo do a 20V 90W one, probably other manufacturers too.