Slugger Gehrig (3)
I believe the answer is:
lou
'slugger gehrig' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lou that I've seen before include "Male or female" , "--- Costello, US comic" , "-- Reed, rock musician" , "-- Costello, Abbott's partner" , "-- Reed, singer" .)