Notice sloshed Etonian welcoming non-drinker (9)
I believe the answer is:
attention
'notice' is the definition.
(I've seen this before)
'sloshed etonian welcoming non-drinker' is the wordplay.
'sloshed' indicates an anagram.
'welcoming' means one lot of letters goes inside another (in sense of 'inviting in').
'non drinker' becomes 'tt' (abbreviation for teetotaller).
'etonian' anagrammed gives 'aention'.
'aention' going around 'tt' is 'ATTENTION'.
(Other definitions for attention that I've seen before include "For coverage" , "Applicaton, concentration" , "should be paid to a teller's account?" , "Special care, soldier's position" , "Order given on parade" .)