Cook some spinach efficiently (4)
I believe the answer is:
chef
'cook' is the definition.
(both can mean someone who cooks)
'some spinach efficiently' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'CHEF' can be found hidden inside 'spinach efficiently'.
(Other definitions for chef that I've seen before include "French master" , "Head cook in a restaurant" , "one in the restaurant" , "Principal cook" , "Professional cook" .)