Finish off muck guzzling the stew (6)
I believe the answer is:
dither
'stew' is the definition.
(I've seen this in another clue)
'finish off muck guzzling the' is the wordplay.
'finish off' means to remove the last letter.
'muck' becomes 'dirt' (I've seen this before).
'guzzling' indicates putting letters inside (I've seen this in other clues).
'dirt' with its final letter removed is 'dir'.
'dir' going around 'the' is 'DITHER'.
(Other definitions for dither that I've seen before include "Agitate indecisively" , "Be undecided and somewhat agitated" , "Display of nerves" , "Waver, be indecisive" , "quake" .)