In a large pot, heat the olive oil. Add the minced garlic and diced onion and cook over moderately high heat, stirring, until the vegetables are softened, about 4 minutes. Stir in the flour until incorporated. Add the saffron-infused fish stock and Albariño and bring to a simmer, stirring, until thickened. Add the clams, cover and cook, shaking the pot, until the clams open, about 6 minutes. Discard any clams that do not open. Spoon the clams into bowls. Season the Albariño sauce with salt and pepper, pour it over the clams and serve them with crusty bread.