Drink, light without head (3)
I believe the answer is:
ale
'drink' is the definition.
(type of beer)
'light without head' is the wordplay.
'light' becomes 'pale' (similar in meaning).
'without head' means to remove the first letter.
'pale' with its initial letter removed is 'ALE'.
(Other definitions for ale that I've seen before include "A drink; sounds like become ill" , "Brewery product" , "Traditional beer" , "Light-coloured beer" , "English beer in sales" .)