Yes, Gorilla is wonderful stuff. For such a small dab, I think 2-parts such as Araldite might be better.
Also...... before you stick it back...
Run a bead of clear silicone sealant all along the gap between the sink and the cabinet.
Then... pull the sink down fully onto the cabinet using clamps if you can get some in there. Before gluing the fitting back.
As a last resort (yes, I've done this a few times) sit a couple of concrete blocks on the sink to force it down :o)
Glue the fitting.
Leave it either clamped or weighted overnight...