Snack is near to cook (6)
I believe the answer is:
sarnie
'snack' is the definition.
(informal term for a sandwich)
'is near to cook' is the wordplay.
'to cook' is an anagram indicator.
'is'+'near'='isnear'
'isnear' with letters rearranged gives 'SARNIE'.
(Other definitions for sarnie that I've seen before include "Bread and filling snack (informal)" , "Two slices of bread with a filling" , "Familiar form of snack" , "Sandwich (informal)" , "Sandwich (slang)" .)