Inventor Sikorsky (4)
I believe the answer is:
igor
'inventor sikorsky' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for igor that I've seen before include "Stravinsky's first name" , "Prince in Borodin's opera" , "Prince --, opera by Borodin" , "Prince of grand opera" , "-- Stravinsky, composer" .)