Expense upsetting Scot (4)
I believe the answer is:
cost
'expense' is the definition.
(cost is a kind of expense)
'upsetting scot' is the wordplay.
'upsetting' is an anagram indicator.
'scot' with letters rearranged gives 'COST'.
(Other definitions for cost that I've seen before include "Be priced at" , "Total spent for goods or services" , "Fee" , "Charge" , "Suffering" .)