Boss sacks one kitchen worker (4)
I believe the answer is:
chef
'kitchen worker' is the definition.
(I've seen this in another clue)
'boss sacks one' is the wordplay.
'boss' becomes 'chief' (synonyms).
'sacks' is a deletion indicator.
'one' becomes 'i' (Roman numeral).
'chief' with 'i' taken away is 'CHEF'.
(Other definitions for chef that I've seen before include "responsible for courses" , "who has a set of knives?" , "one in the restaurant" , "Saucier" , "One who prepares courses" .)