The most untreated and muddied waters (6)
I believe the answer is:
rawest
'the most untreated' is the definition.
I can't judge whether this definition defines the answer.
'muddied waters' is the wordplay.
'muddied' is an anagram indicator (I've seen 'muddy' mean this (I've seen this in other clues)).
'waters' with letters rearranged gives 'RAWEST'.
'and' is the link.
Can you help me to learn more?
(Other definitions for rawest that I've seen before include "Like most recent recruits, perhaps" , "Least cooked and most unpleasantly cold" .)