Live successfully on old money (5)
I believe the answer is:
dwell
'live' is the definition.
(to live/dwell somewhere)
'successfully on old money' is the wordplay.
'successfully' becomes 'well' (I've seen this in other clues).
'on' says to put letters next to each other.
'old money' becomes 'd' ().
'well' put after 'd' is 'DWELL'.
(Other definitions for dwell that I've seen before include "Abide, reside" , "stay" , "Focus attention (on)" , "Hang out" , "Reside - linger" .)