Edible seed (6)
(Other definitions for kernel that I've seen before include "Nut's centre" , "Edible or central part of nut" , "Edible seed of nut" , "Inner seed of nut" , "Stone" .)
'edible seed' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for peanut that I've seen before include "grows in the ground" , "Eat pun for the hard fruit" , "Bar nibble" , "Leguminous seed eaten as snack or butter" , "sort of butter" .)
(Other definitions for lentil that I've seen before include "Pulse used in cooking" , "Edible leguminous plant seed" , "'Seed, pulse (6)'" , "bit of food" , "A legume, its seed" .)