Possible Clues:

• 'Straight Outta Compton' role, familiarly
• Snoop's 'Deep Cover' collaborator
• 50 Cent mentor
• Rapping MD?
• Rap Dr
• Beats by Dr. ___ (headphone brand)
• 'Dr.' with Grammys
• Beats Music VIP
• Rap music's Dr. --
• Rap's 'Dr.'