Xmas booze g-g-gone astray (6)
I believe the answer is:
eggnog
'xmas booze' is the definition.
(drink often drunk at Christmas)
'g-g-gone astray' is the wordplay.
'g-g-gone' becomes 'g-ggone' ('ggone' said with a stutter like 'g-gone' was; 'gone' said with a stutter like 'gone' was).
'astray' is an anagram indicator.
'gggone' anagrammed gives 'EGGNOG'.
(Other definitions for eggnog that I've seen before include "Drink (milk punch)" , "Yellowish mixed alcoholic drink" , "Rum-based drink" , "Drink of milk or cream, eggs and alcohol" , "Milky winter punch" .)