A lot of people loosen the brackets that attach your clutch or brake assembly to the handle bar, so in case of an accident the assembly will spin rather than break. But its difficult to get the right tension and the friction factor changes with water, mud, etc. which can cause the assembly to work its way loose and move while riding.
I find the best idea is to wrap Teflon tape (plumbers tape) around the handle bar where the the clutch and brake assembly will be mounted. The Teflon is frictionless, so you can still tighten your clamps firm but it allows the assembly to spin with force in the event of a crash, but not rattle loose while riding.