Heat ¼ cup oil in a medium Dutch oven or other heavy pot with a lid over medium-high. Add fennel and leek and season with salt. Cook, stirring often, until vegetables are starting to soften, about 3 minutes. Add garlic and corn and cook, stirring, until garlic is translucent, about 1 minute. Add ¼ cup water and simmer until corn is bright yellow and starting to soften, about 2 minutes. Add wine and simmer until slightly reduced, about 30 seconds. Add clams, cover pot, and reduce heat to medium. Cook, stirring occasionally, until clams open, 8–12 minutes. Discard any clams that have not opened. Top with parsley, chives, and a few pinches of red pepper flakes and drizzle with oil. Serve with grilled bread for soaking up pan sauces.