Tycoon, magnate (5)
I believe the answer is:
nabob
I believe this clue is a double definition.
'tycoon' is the first definition.
(thesaurus)
'magnate' is the second definition.
(I've seen this in another clue)
(Other definitions for nabob that I've seen before include "Magnate; formerly one with Eastern wealth" , "Rich British merchant in India" , "Mogul governor; very rich or important person" , "Mogul governor; rich man" , "Fat cat: governor in India during the Mogul empire" .)