City in Michigan removing old American debris (8)
I believe the answer is:
detritus
'debris' is the definition.
(I know that debris can be written as detritus)
I don't understand the rest of the clue.
(Other definitions for detritus that I've seen before include "Left over bits and pieces" , "Loose material worn away from rocks" , "Waste, debris" , "waste material" , "Remains" .)