Did he keep changing his viewpoint as an artist? (6)
I believe the answer is:
turner
'artist?' is the definition.
(painter JMW Turner)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for turner that I've seen before include "potter" , "Prize < for artist" , "J. M. W. -, English eighteenth to nineteenth century painter" , "British landscape painter - US rock singer, Tina" , "Skilled tradesman or great English painter." .)