Great to pass one day swigging litres (8)
I believe the answer is:
splendid
'great' is the definition.
(thesaurus)
'pass one day swigging litres' is the wordplay.
'pass' becomes 'spend' ('spend' can be a synonym of 'pass'**).
'one' becomes 'i' (Roman numeral).
'day' becomes 'd'.
'swigging' means one lot of letters goes inside another.
'litres' becomes 'l'.
'spend'+'i'+'d'='spendid'
'spendid' placed around 'l' is 'SPLENDID'.
'to' acts as a link.
(Other definitions for splendid that I've seen before include "Grand" , "Excellent, first-class" , "Marvellous" , "Magnificent, brilliant" , "Wonderful" .)