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' suggests deleting specific letters.
'one' becomes 'i' (Roman numeral).
'chief' with 'i' taken out 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" .)