Calculate that man will stay the course until death (2,3,4)
I believe the answer is:
to the last
'until death' is the definition.
(I've seen this before)
'calculate that man will stay the course' is the wordplay.
I cannot quite see how this works, but
'calculate' could be 'tot' (I've seen this before) and 'tot' is present in the answer.
'man' could be 'he' (he refers to a man) and 'he' is located in the answer.
'stay' could be 'last' and 'last' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for to the last that I've seen before include "Presumably a rallying call to encourage cobbler" , "till you die!" , "Until death" , "Back to work, Hans Sachs" .)