Pour in the wine and turn the heat up slightly. Cook until the wine has reduced to barely 1 tbsp. Pour in the tomatoes, rinsing the can out with a splash of water. Simmer for 5 mins, then stir in the rocket, crayfish and the cooked pasta. Mix well to combine, stirring in a little of the reserved pasta water and the butter to create a sauce. Cut the zested lemon in half and squeeze one half over the pasta, then cut the other half into wedges.
