Clean calamari. Cut into 1/2-inch rings. Combine lemon juice and 3 tablespoons olive oil in a medium bowl. Add calamari and let marinate for 30-45 minutes.
Cook orzo in a separate pot of boiling salted water until al dente (about 8-10 minutes). Drain and place in a large bowl or serving dish.
In a large saucepan, add remaining 4 tablespoons of olive oil. Add onion and garlic and sauté for 3-5 minutes. Add calamari and cook until limp, about 8-10 minutes. Add white wine and cook for 3 minutes. Pour over cooked orzo and stir well. Adjust seasonings with salt and freshly ground pepper. Serve at room temperature or cold.