Fourteen others were also wounded in Sunday's attack in the city of Jalalabad, a hospital official told Al Jazeera.
Ataullah Khyogani, spokesman for the Nangarhar provincial government, said the attacker detonated his explosives at about 10:30am local time at the residential compound of Obaidullah Shinwari.
Among the wounded was Shinwari's father, Malik Osman, who is a prominent tribal elder and a fierce critic of the Islamic State in Iraq and the Levant (ISIL) group, said Attaullah Khugyani, a spokesman for Nangarhar's governor.
The attack came just days after a deadly asault on the Pakistani consulate in Jalalabad, close to Shinwari's compound, that was claimed by ISIL.
Khyogani said a guesthouse on the compound was crowded with people invited to a family event.
Al Jazeera's Omar al-Saleh said the tribal elder was among the wounded.
"We believe the suicide bomber was disguised as a guest," he reported from the capital Kabul. "The situation is Jalalabad is very volatile. You have both the Taliban and ISIL present there. The two groups are not only fighting the government, but also each other."
Taliban spokesman Zabiullah Mujahid said the group was not responsible for Sunday's attack.