A bird might see it as food (4)

I believe the answer is:

grub

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'food' is the definition.
(grub can informally mean food)

I cannot understand how the rest of the clue works.

(Other definitions for grub that I've seen before include "Dig (up); hack writers' Street" , "Caterpillar - food" , "ferret > eats" , "Table needs" , "Food (informal)" .)

I've seen this clue in the Evening Standard.

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