Dish produced by office worker and posh artist (7)
I believe the answer is:
tempura
'dish' is the definition.
(tempura is a kind of dish)
'office worker and posh artist' is the wordplay.
'office worker' becomes 'temp' (short for temporary worker).
'and' means one lot of letters go next to another.
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-U).
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'temp'+'u'+'ra'='TEMPURA'
'produced by' is the link.
(Other definitions for tempura that I've seen before include "Japanese battered dish" , "Japanese dish fried in batter" , "Japanese food deep-fried in batter" , "Japanese food fried in batter" , "Food that's been dipped in batter and deep-fried" .)