Just heard Dicky's a total loss (5-3)
I believe the answer is:
write-off
'a total loss' is the definition.
(I know that total loss can be written as write-off)
'just heard dicky's' is the wordplay.
'just' becomes 'right' (similar in meaning).
'heard' indicates a 'sounds like' (homophone) clue.
'dicky' becomes 'off'.
'right' sounds like 'write'.
'write'+'off'='WRITE-OFF'
(Other definitions for write-off that I've seen before include "Article beyond repair" , "Send a letter - cancel a debt" , "Cancel like bad debt" , "Cancel, a debt perhaps" , "To destroy irredeemably" .)