Cook some spinach effectively (4)
I believe the answer is:
chef
'cook' is the definition.
(both can mean someone who cooks)
'some spinach effectively' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'CHEF' is hidden in the letters of 'spinach effectively'.
(Other definitions for chef that I've seen before include "Kitchen head" , "Head cook in a restaurant" , "member of kitchen staff" , "Principal cook" , "one in the restaurant" .)