Ended chief’s expense (8)
I believe the answer is:
overhead
'expense' is the definition.
(I know that overhead is a type of expense)
'ended chief's' is the wordplay.
'ended' becomes 'over' (synonyms).
'chief' becomes 'head' (synonyms).
'over'+'head'='OVERHEAD'
(Other definitions for overhead that I've seen before include "Aloft" , "An expense in curred in maintaining property" , "Expenses" , "In the sky - type of door or projector" , "Operating cost" .)