Penniless from being part Greek - or by not saving, on reflection (5-5)
I believe the answer is:
stony-broke
'penniless' is the definition.
(informal term meaning without money)
'being part greek or by not saving on reflection' is the wordplay.
'being part' indicates a hidden word.
'on reflection' says the letters should be written backwards.
'ekorbynots' is hidden in the letters of 'greek or by not saving'.
'ekorbynots' reversed gives 'STONY-BROKE'.
'from' acts as a link.
(Other definitions for stony-broke that I've seen before include "Penniless" , "Utterly skint" .)