Pet food? (4)
I believe the answer is:
chow
I believe this clue is a double definition.
'pet' is the first definition.
(I know that chow is a type of dog)
'food?' is the second definition.
(chow can informally mean food)
(Other definitions for chow that I've seen before include "Mixed < dog" , "[HOUND]" , "Long-haired dog of Chinese breed, or informal food" , "Food (colloq.)" , "Long-haired Chinese dog or slangy food" .)