Dies poor and in regret: what's left? (7)
I believe the answer is:
residue
'what's left?' is the definition.
(residue means what's left behind)
'dies poor and in regret' is the wordplay.
I cannot really see how this works, but
an anagram of 'dies' is 'esid' which is located in the answer.
'regret' could be 'rue' (to rue something is to regret it) and 'rue' is present in the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for residue that I've seen before include "Remains to be seen" , "What is left, maybe dregs" , "Surplus" , "Whatever is left over" , "Remainder, leftover" .)