Idyllic place where a painter captures Muslim judge (7)
I believe the answer is:
arcadia
'idyllic place' is the definition.
(imagined utopian place)
'a painter captures muslim judge' is the wordplay.
'painter' becomes 'RA' (member of the Royal Academy of Arts).
'captures' indicates putting letters inside.
'muslim judge' becomes 'cadi' (Islamic term for a judge).
'ra' enclosing 'cadi' is 'rcadia'.
'a'+'rcadia'='ARCADIA'
'where' is the link.
(Other definitions for arcadia that I've seen before include "rural area" , "pastoral country" , "Idyllic country of song-loving shepards" , "Poetically the home of songloving shepherds" , "In Greece, its capital is Tripoli" .)