Left squire dancing, having consumed posh drinks (8)
I believe the answer is:
liqueurs
'drinks' is the definition.
(liqueur is a kind of drink)
'left squire dancing having consumed posh' is the wordplay.
'left' becomes 'l' (common abbreviation**).
'dancing' is an anagram indicator.
'having consumed' means one lot of letters goes inside another.
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-u).
'squire' with letters rearranged gives '[squire]'.
'l'+'[squire]'='l[squire]'
'liquers' placed around 'u' is 'LIQUEURS'.
(Other definitions for liqueurs that I've seen before include "Sweetened spirits" , "Strong sweet alcoholic spirits for after meals" , "Strong, highly flavoured drinks" , "Tasty alcoholic post-dinner drinks" , "Sweet after-dinner alcoholic drinks" .)