Short form filled in by good business leader (5)
I believe the answer is:
mogul
'business leader' is the definition.
(I know that business leader can be written as mogul)
I cannot understand how the remainder of the clue works.
(Other definitions for mogul that I've seen before include "Important person; snow mound on a ski slope" , "Former Indian ruler; bump on a ski slope" , "Big cheese - mound of hard snow on a ski slope" , "bigwig" , "Very wealthy or powerful business person" .)