No source of money remains (3)
I believe the answer is:
ash
'remains' is the definition.
(I've seen this before)
'no source of money' is the wordplay.
'no source of' means to remove the first letter.
'money' becomes 'cash' (I've seen this before).
'cash' with its first letter taken off is 'ASH'.
(Other definitions for ash that I've seen before include "Tree with winged seeds" , "Volcanic dust" , "Tree with keys" , "It no longer burns" , "It's used for flooring" .)