Mixed drink, say, going off without one (6)
I believe the answer is:
eggnog
'mixed drink' is the definition.
(I know that eggnog is a type of mixed drink)
'say going off without one' is the wordplay.
I cannot really see how this works, but
'say' could be 'eg' (both can mean 'for example') and 'eg' is present in the answer.
'without' could be 'no' and 'no' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for eggnog that I've seen before include "Yellowish mixed alcoholic drink" , "Xmas tipple" , "Drink similar to advocaat" , "Punch comprising cream and other farm produce" , "Winter cocktail" .)