In default Im a tallyman accepting the last offers (8)
I believe the answer is:
ultimata
'the last offers' is the definition.
(I've seen this before)
'in default im a tallyman accepting' is the wordplay.
'in' indicates a hidden word.
'ULTIMATA' can be found hidden inside 'default im a tallyman accepting'.
(Other definitions for ultimata that I've seen before include "Final offers" , "Final demands" , "Last offers" .)