Posh daily purchased by choice in capital (9)
I believe the answer is:
bucharest
'capital' is the definition.
(capital of Romania)
'posh daily purchased by choice' is the wordplay.
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-U).
'daily' becomes 'char' (both can mean a cleaner).
'purchased by' means one lot of letters goes inside another (inserted letters are acquired or purchased).
'choice' becomes 'best' (I've seen this in other clues).
'u'+'char'='uchar'
'uchar' placed within 'best' is 'BUCHAREST'.
'in' is the link.
(Other definitions for bucharest that I've seen before include "Balkan city" , "European capital" , "European city" , "Romanian capital" , "Capital of Romania" .)