Glum (8)
(Other definitions for downbeat that I've seen before include "Conductor is likely to make this movement" , "Pessimistic, gloomy" , "Understated; gloomy" , "Casual" , "Miserable; relaxed" .)
(Other definitions for downcast that I've seen before include "Dispirited, gloomy" , "Feeling despondent" , "Depressed - looking at the floor?" , "disheartened" , "Crestfallen" .)