Gravy problem (4)
I believe the answer is:
lump
'gravy problem' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lump that I've seen before include "Shapeless mass - swelling" , "Small shapeless mass" , "Swelling; ungainly person" , "Node" , "Irregularly shaped piece" .)