Beverage for outspoken wagoners . . . (5)
I believe the answer is:
lager
'beverage' is the definition.
(lager is a kind of beverage)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for lager that I've seen before include "Tipple" , "light ale" , "Bottom-fermented beer" , "A regal sort of drink" , "Effervescent beer" .)