An old, old boy coming back from the wine shop (6)
I believe the answer is:
bodega
'the wine shop' is the definition.
(I've seen this before)
'an old old boy coming back' is the wordplay.
'an old' becomes 'aged' (I've seen this before).
'old boy' becomes 'OB' (abbreviation for a private school 'old boy').
'coming back' is a reversal indicator.
'aged'+'ob'='agedob'
'agedob' back-to-front is 'BODEGA'.
'from' acts as a link.
(Other definitions for bodega that I've seen before include "Small Spanish grocery and wine store" , "Span. wine shop" , "concern for alcohol" , "winestore" , "Spanish wine-shop" .)