To an artist, simply desert; but actually it's a mountain (6)
I believe the answer is:
ararat
'it's a mountain' is the definition.
(Turkish mountain)
'to an artist simply desert but actually' is the wordplay.
I cannot quite see how this works, but
'an' could be 'a' and 'a' is found within the answer.
'artist' could be 'ra' (Royal Academician, member of Royal Academy of Arts) and 'ra' is found within the answer.
'desert' could be 'rat' (abandon treacherously) and 'rat' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ararat that I've seen before include "Famous dry spot" , "Mountain where the Ark grounded" , "Turkish Mount said to contain Noah's Ark" , "Biblical mountain" , "Biblical mount" .)