Artist changing evermore, losing nothing (7)
I believe the answer is:
vermeer
'artist' is the definition.
(Johannes Vermeer, 1632-1675)
'changing evermore losing nothing' is the wordplay.
'changing' indicates an anagram.
'losing' is a deletion indicator.
'nothing' becomes 'O' (O resembles 0).
'evermore' with 'o' taken away is 'evermre'.
'evermre' is an anagram of 'VERMEER'.
(Other definitions for vermeer that I've seen before include "Jan -, seventeenth century Dutch painter" , "Dutch painter, 1673-75" , "Dutch painter, 1632-75" , "'Dutch painter, noted for his use of light (7)'" , "Painter of Girl with a Pearl Earring, d. 1675" .)