Ante up for the kernel (6)
I believe the answer is:
peanut
'ante up for the kernel' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for peanut that I've seen before include "It ripens in a vine pod underground" , "foodstuff" , "Ante up for this type of hard fruit" , "Item of fruit" , "Monkey nut" .)