Dark brush changing hands (5)
I believe the answer is:
gloom
'dark' is the definition.
(gloom is a kind of dark)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for gloom that I've seen before include "Dimness" , "Partial darkness" , "Murk" , "Dark depression?" , "Obscurity or melancholy" .)