Lake's gold reflection portrayed by Turner (7)
I believe the answer is:
rotorua
'lake's' is the definition.
(Lake Rotorua in New Zealand)
'gold reflection portrayed by turner' is the wordplay.
'gold' becomes 'Au' (Au is the chemical symbol for gold).
'reflection' is a reversal indicator.
'portrayed by' says to put letters next to each other.
'turner' becomes 'rotor' (something that turns).
'au' reversed gives 'ua'.
'ua' put after 'rotor' is 'ROTORUA'.
(Other definitions for rotorua that I've seen before include "NZ city of geysers and hot mud pools" , "NZ resort" .)