Yes, duet is a noun, a singular common noun.
The sentence has both an object and a pronoun:his, a pronoun called a possessive adjective;duet, a noun that is direct object of the verb 'will sing';concert, a noun that is object of the preposition 'in'.
Duet
It is called a DuetDuet
A duet is a duet, regardless of the sexes of the singers.
A song sung by two people is called a duet
The Flower Duet is about flowers.
A duet
They sang a duet
A duet
Duo? otherwise, duet...
Can You Duet ended in 2009-06.
A duet is when you do it with another person. (2) A solo is when you do it alone. (1) So, if you do it with a duet, you have a trio.