Red Army, drunk on vodka drink (6,4)
I believe the answer is:
bloody mary
'vodka drink' is the definition.
(I've seen this in another clue)
'red army drunk on' is the wordplay.
'red' becomes 'bloody' (I can't explain this - if you can you should believe this answer much more).
'drunk' indicates anagramming the letters.
'on' means one lot of letters goes inside another (as in clothing 'on' a person).
'army' is an anagram of 'mary'.
'bloody' placed within 'mary' is 'BLOODY MARY'.
Can you help me to learn more?
(Other definitions for bloody mary that I've seen before include "something to drink" , "Nickname of Henry VIII's first daughter" , "killing Queen?" , "Vodka-based cocktail" , "Tomato juice and vodka" .)