Baseball great Musial (4)
I believe the answer is:
stan
'baseball great musial' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stan that I've seen before include "- Getz, jazz musician" , "guy" , "Laurel perhaps" , "Eminem hit; man's name" , "Ollie's partner" .)