Nothing left that's acceptable? (3,5)
I believe the answer is:
all right
I believe this clue is a double definition.
'nothing left' is the first definition.
(I've seen this before)
'acceptable?' is the second definition.
(I've seen this before)
'that's' is the link.
(Other definitions for all right that I've seen before include "Very well, as you ask - everything's fine" , "What's clearly acceptable" , "Allowable; fairly well" , "Yes - adequate" , "No problem" .)