Knock back some elderberry wine (3)
I believe the answer is:
Here is my best explanation:
'wine' is the definition.
(red wine is a kind of wine)
'knock back some elderberry' is the subsidiary indication.
'knock back' says the letters should be written in reverse.
'some' says the answer is hidden in the clue (Some of the parts of the word are used).
'der' can be found hidden inside 'elderberry'.
'der' reversed gives 'red'.
(Other definitions for red that I've seen before include "Looking embarrassed", "Carmine", "Ruby", "Blushing", "Colour of Merlot wine", "Flushed", "Merchant flag", "Colour of communism", "Colour of 1 across" and "Colour of garnets".)