Drunk on drink, have a meal (4,3)
I believe the answer is:
high tea
'a meal' is the definition.
(high tea is a kind of meal)
'drunk on drink' is the wordplay.
'drunk' becomes 'high' (I've seen this before).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'drink' becomes 'tea' (tea is a drink).
'high'+'tea'='HIGH TEA'
'have' acts as a link.
(Other definitions for high tea that I've seen before include "Early evening meal" , "Early-evening meal" , "A lofty kind of evening meal" , "Late afternoon meal which includes a cooked dish" , "Late-afternoon meal" .)