Put the pasta into a pan of boiling water and cook following the packet instructions. Drain.
Meanwhile, heat the oil in a saucepan and add the leek and chilli. Fry gently for 5 mins, making sure the leek doesn't brown. Add the crab meat and lemon zest, then a little of the juice, to taste.
Take off the heat, season, and stir the crab mixture through the pasta.