Search for food (4)
I believe the answer is:
grub
I believe this clue is a double definition.
'search' is the first definition.
(grubbing is a kind of searching)
'food?' is the second definition.
(grub is a kind of food)
'for' is the link.
(Other definitions for grub that I've seen before include "Larva; dig shallowly" , "Food (informal)" , "Larva; food (sl.)" , "Nosh - larva" , "Caterpillar - food" .)