Unpopular revenue generator possibly shares around excessive returns (5,4)
I believe the answer is:
speed trap
'unpopular revenue generator' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'shares around excessive returns' is the wordplay.
'shares' becomes 'parts' (share can mean a part or division of something).
'around' means one lot of letters goes inside another.
'excessive' becomes 'deep' (I can't justify this - if you can you should believe this answer much more).
'returns' says the letters should be written in reverse.
'parts' enclosing 'deep' is 'partdeeps'.
'partdeeps' reversed gives 'SPEED TRAP'.
'possibly' is the link.
Can you help me to learn more?
(Other definitions for speed trap that I've seen before include "curse of drivers?" , "police operation" , "road safety measure" , "Set-up to catch fast drivers" , "Hazard for fast motorist" .)