Total loss (5-3)
I believe the answer is:
write-off
'total loss' is the definition.
(I know that total loss can be written as write-off)
This is the entire clue.
(Other definitions for write-off that I've seen before include "Cancel, a debt perhaps" , "To destroy irredeemably" , "Send a letter - complete failure" , "Article beyond repair" , "Give up on, recognise as lost like bad debt" .)