Baseball player in jug (7)
I believe the answer is:
pitcher
I believe this is a double definition.
'baseball player' is the first definition.
(I know that pitcher is a type of baseball player)
'jug?' is the second definition.
(I know that pitcher is a type of jug)
'in' is the link.
(Other definitions for pitcher that I've seen before include "able to hold a lot of beer" , "Does one throw the vessel?" , "Earthenware jug" , "crock" , "source of drink?" .)