Alexander ___, Russian chemist and composer whose music was adapted for the musical Kismet (7)
I believe the answer is:
borodin
(Other definitions for borodin that I've seen before include "Russian composer, Aleksandr Porfirevich (1834-87)" , "Noteworthy chap" , "Russian composer, d. 1887" , "Prince Igor composer, d. 1887" , "Russian composer (Prince Igor)" .)