Beer that's light and headless (3)
I believe the answer is:
ale
'beer' is the definition.
(type of beer)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ale that I've seen before include "Alcoholic drink" , "festival" , "Alcohol" , "Alcoholic beverage" , "Beerlike beverage" .)