The achievement of a teetotaller isn't commonly welcoming people (10)
I believe the answer is:
attainment
'the achievement' is the definition.
(attainment is a kind of achievement)
'a teetotaller isn't commonly welcoming people' is the wordplay.
'teetotaller' becomes 'tt' (abbreviation).
'isn't commonly' becomes 'aint' (I've seen this in other clues).
'welcoming' is an insertion indicator (in sense of 'inviting in').
'people' becomes 'men' (man is a kind of person).
'aint' placed around 'men' is 'ainment'.
'a'+'tt'+'ainment'='ATTAINMENT'
'of' acts as a link.
(Other definitions for attainment that I've seen before include "Laudable exploit" , "Act of achieving something" , "The achievement (of a goal)" , "Realisation" , "Feat achieved" .)