Stir the flour, sugar and salt together in a large bowl. Grate or shred the cold butter over the flour mixture, stopping occasionally to toss butter with flour mixture. When the whole stick of butter has been added, stir mixture with a fork or use your fingers to make the mixture evenly coarse.
Add water 1 tablespoon at a time and stir with a heavy duty scraper until dough comes together. Shape into ball. Wrap in plastic and keep chilled until ready to use or use immediately.
Filling: Separate syrup from cherries and measure out 3/4 cup of the syrup.
In a large saucepan, stir together sugar and cornstarch. Whisk in the cherry syrup, then set over medium heat. Whisk the mixture until it thickens and becomes translucent. Remove from heat and stir in butter, lemon juice and extract, then stir in the drained cherries.
Pie Assembly: Preheat the oven to 400 degrees F. and put a heavy rimmed baking sheet in the oven. You'll be baking the pie on the hot, preheated cookie sheet (which is supposed to help keep the crust crisp).
On a lightly floured surface, roll dough into a 12 inch circle. Transfer to a 9 inch round pie tin and crimp edges. Pour filling in the center of the pie.
Topping: Combine the flour, oats, sugar, salt and cinnamon in the bowl you used for your pie crust. Add butter and stir until crumbly, then sprinkle over pie filling.
Set the pie on the hot baking sheet and put it in the oven.
Reduce the heat to 375 degrees F. and bake for 40 minutes. Check after 30 minutes to make sure your crumb topping isn't browning too quickly. If it is, lay a sheet of foil over it.
Let the pie cool before serving.