Cook some lunch effortlessly (4)
I believe the answer is:
'cook' is the definition.
(chef is a kind of cook)
'some lunch effortlessly' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'CHEF' can be found hidden inside 'lunch effortlessly'.
(Other definitions for chef that I've seen before include "Professional cook" , "Chief male cook in restaurant" , "who has a set of knives?" , "one in the restaurant" , "Kitchen head" .)