Model gets disheartened over artist's range (6)
I believe the answer is:
sierra
'range' is the definition.
(sierra is a kind of range)
'model gets disheartened over artist's' is the wordplay.
I cannot really see how this works, but
'artist' could be 'ra' (Royal Academician, member of Royal Academy of Arts) and 'ra' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sierra that I've seen before include "A Spanish mountain chain (6)" , "letter read out on the radio" , "Long range" , "Jagged mountain range" , "International codeword" .)