Heat olive oil in a large stockpot or casserole over medium-high heat until hot, 2 to 3 minutes. Add leeks and garlic; stir to coat. Cook, stirring, until leeks are softened but not brown, about 3 minutes. Add red-pepper flakes, smoked turkey wing, and greens; if necessary add greens in several batches.
Add wine; cover. Steam greens, turning occasionally, 8 to 10 minutes. Uncover, add salt and pepper, and cook, tossing occasionally, 3 minutes more. Discard turkey and garlic, and serve.