A "rap account" is an alternate name for a fee-based advisory account. The correct pphrase is actually a "Wrap Account" since the fee paid for that type of service is generally considered an all-inclusive "wrapper" that covers trading and rebalancing costs. Those costs are paid by the investor on an "as used" basis in brokerage accounts. Trading ticket charges and sales commissions are typically waived in a "wrap account" platform in lieu of a quarterly advisory fee.
Dr. Dre, Jay Z, Drake and A Tribe Called Quest are all great examples of Rap. I think you are referring to Wrap, which is a fee-based account.