High-flyers succeeded at business (7)
I believe the answer is:
pigeons
'high-flyers' is the definition.
'succeeded at business' is the wordplay.
'succeeded' becomes 's' (genealogical abbreviation).
'at' says to put letters next to each other (I've seen this in other clues).
'business' becomes 'pigeon' (pigeon can mean someone's business or affairs).
's' put after 'pigeon' is 'PIGEONS'.
(Other definitions for pigeons that I've seen before include "Spin ego around the birds" , "Town birds" , "Columbiform birds" , "Cooing birds" , "traditional pie filling" .)