The lion will only eat the shrinp. You could definitely keep a star. Lions are groupers PRETTY MUCH, and my grouper and trigger don't bother any inverts except for shrimp. I currently have 2 stars, many snails, hermits, etc with my fish and they're fine. And if you do decide on the lion, a fu Manchu would be the best by far.
150g. Honeycomb grouper, yellow tang, niger triggerfish, orbiculate batfish, black edge moray, and huma huma trigger. Green star polyps, gorgonian, toadstool, goniopora, anthelia, and torch.