For the compote: Combine the strawberries, sugar, cinnamon and 1/4 cup water in a medium skillet. Bring to a simmer over medium-high heat, then reduce the heat to medium and simmer, stirring occasionally and coarsely mashing the berries with a spoon, until the strawberries are tender and the liquid has thickened, about 12 minutes. Transfer to a bowl and cool completely.
For the scones: Preheat the oven to 375 F. Line a rimmed baking sheet with parchment paper.
Pulse the flour, 1/2 cup sugar, baking powder, lemon zest and salt together in a food processor until well combined. Add the butter and pulse until the mixture resembles a coarse meal. Add the cream, egg and vanilla and pulse until the dough starts to come together. Turn the dough out onto a piece of parchment paper; gather it up and form it into a disc about 3/4-inch thick and 7 inches in diameter. Cut the disc into 8 triangles and transfer to the prepared baking sheet; sprinkle with the remaining 1 tablespoon sugar.
Bake until golden brown on the bottom and pale golden on top, about 15 minutes.
Serve the scones warm or room temperature, with clotted cream and strawberry compote.