"Bonanza” star Lorne (6)
I believe the answer is:
greene
'bonanza star lorne' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for greene that I've seen before include "Graham -, twentieth century English author" , "writer" , "See 13" , "Graham --, British author" , "The Quiet American author" .)