"Mental Illness" Grammy winner Aimee (4)
I believe the answer is:
mann
(Other definitions for mann that I've seen before include "German writer concerned with the role of the artist in society, d. 1955" , "Keyboard player Manfred" , "Manfred --, 1960s pop band" , "See 23 Across" , "Thomas --, German writer (Death in Venice)" .)