It grows on cobs (4)
I believe the answer is:
corn
'it grows on cobs' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for corn that I've seen before include "Cereal crop; callus" , "digital growth" , "Painful foot problem" , "In song from 'Oklahoma' this is as high as an elephant's eye" , "Get drunk commonly" .)