King, a Northumbrian one, first to enjoy alcoholic drink (3,4)
I believe the answer is:
red wine
'alcoholic drink' is the definition.
'red wine' can be an answer for 'drink' (red wine is a kind of drink). I'm not sure about the 'alcoholic' bit.
'king a northumbrian one first to enjoy' is the wordplay.
'king' becomes 'r' (r is abbreviation for rex).
'a northumbrian one' becomes 'edwin' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'first to' says to take the initial letters.
The initial letter of 'enjoy' is 'e'.
'r'+'edwin'+'e'='RED WINE'
Can you help me to learn more?
(Other definitions for red wine that I've seen before include "Tent, say" , "Burgundy perhaps" , "Vin rouge, like claret" , "Eg, claret" , "Such as Shiraz or Merlot" .)