By Nichola Saminather TORONTO, Nov 18 (Reuters) - Surging inflation and rising bond yields are set to offer a shot in the arm for Canadian banks' profit margins, which have languished during the pandemic, but an aggressive response by central banks could derail a nascent lending recovery and increase defaults, investors and analysts said. But uncertainty around how persistent inflation will be and how quickly rates will rise is clouding the outlook for lending recovery into next year that investors had hoped for. BOCWATCH "Grocery prices, cars, everything that people buy is getting more expensive," Driscoll added.