Drop litter and stuff (3)
I believe the answer is:
Here is my best explanation:
This clue is a double definition.
'drop litter' is the first definition.
('pig' can mean to give birth to a litter of pigs)
'stuff' is the second definition.
(both can mean to eat lots of food)
'and' is the link.
(Other definitions for pig that I've seen before include "Greedy person (colloq.)", "Eg, sow", "Unforged metal", "Greedy eater", "Farmyard animal", "quantity", "Boar or sow", "Eat greedily", "Glutton" and "Difficult task".)