Twisted mass (6)
I believe the answer is:
tangle
'twisted mass' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tangle that I've seen before include "Snarl or embroil" , "Confused mess" , "Seaweed; confusion" , "Confused situation; a seaweed" , "A fight; seaweed" .)