Oozy gunk (3)
I believe the answer is:
goo
'oozy gunk' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for goo that I've seen before include "Slime" , "mud, for example" , "syrup" , "Sticky substance (colloq.)" , "Sticky or slimy substance" .)