Clue: Con-artist's seldom discovered casing wealthy place (2,6)
Answer: EL DORADO
Explanation: Definition: wealthy place
 [ DO(to con/to swindle) + RA(abbrev. for a member of the Royal Academy of Arts/an artist) ] **contained in**(… casing) "seldom" **minus ****its 1st and last letters**(discovered).
Defn: A legendary … where precious stones and gold coins were found in abundance.