Write off an amount (5)
I believe the answer is:
total
I believe this is a double definition.
'write off' is the first definition.
(both can mean to permanently damage something)
'an amount' is the second definition.
(I know that amount can be written as total)
(Other definitions for total that I've seen before include "Whole amount" , "Including all" , "The whole, sum" , "Absolute; sum" , "Completely destroy" .)