Blue steady light, not good (3)
I believe the answer is:
low
'blue' is the definition.
(both can mean sad)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for low that I've seen before include "Opposite of high" , "Humble; dejected" , "Depressed or base" , "Depressed; near the ground" , "Unimportant sort of owl" .)