Vessels for baseball players (8)
I believe the answer is:
pitchers
This clue is a double definition.
'vessels' is the first definition.
(pitcher is a kind of vessel)
'baseball players' is the second definition.
(pitcher is a kind of baseball player)
'for' is the link.
(Other definitions for pitchers that I've seen before include "American sportsmen" , "Water-carriers" , "Ewers" , "Players" , "They can carry water" .)