Steal money off of popular singer (5)
I believe the answer is:
robin
'singer' is the definition.
(robins are songbirds)
'steal money off of popular' is the wordplay.
I cannot really see how this works, but
'steal' could be 'rob' (robbing is a kind of stealing) and 'rob' is found in the answer.
'popular' could be 'in' (something that's 'in' is fashionable) and 'in' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for robin that I've seen before include "Popular British bird" , "Batman's helper" , "Small songbird" , "Bird, killed by Sparrow" , "Red-breasted songbird" .)