Business magnate (5)
'business magnate' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tycoon that I've seen before include "Rich businessperson" , "Powerful industrialist" , "top businessman" , "Big cheese in business" , "See 2" .)
(Other definitions for mogul that I've seen before include "big shot" , "Bashaw" , "Tycoon -- ski slope mound" , "Powerful businessperson" , "Big cheese - mound of hard snow on a ski slope" .)