Unclear; dirty (5)
I believe the answer is:
muddy
I believe this is a double definition.
'unclear' is the first definition.
(I've seen this in another clue)
'dirty' is the second definition.
(I know that dirty can be written as muddy)
(Other definitions for muddy that I've seen before include "Bespattered" , "Slimy" , "Not bright or clear" , "Mucky, marshy" , "Covered in mire" .)