Will transferring a Roth IRA from one brokerage to another restart the five year profit withdrawal clock?

No, transferring a Roth IRA from one brokerage to another does not restart the five-year clock for profit withdrawals. The five-year period pertains to the first contribution made to any Roth IRA you own, not the specific account. As long as you are over the age of 59½ and have met the five-year requirement, you can withdraw earnings tax-free regardless of the transfer.