Uniformly brownish attire? (6)
I believe the answer is:
livery
'uniformly brownish attire?' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps there's an association between them I don't understand?
This is the entire clue.
Can you help me to learn more?
(Other definitions for livery that I've seen before include "Uniform, eg of guild" , "Irritable" , "outfit in uniform" , "The stabling and care of horses" , "Uniform -- suffering from gastric distress" .)