Not one famous painter is a superhuman person (5)
I believe the answer is:
titan
'superhuman person' is the definition.
'titan' can be an answer for 'person' (titan is a kind of person). I'm not certain of the 'superhuman' bit.
'not one famous painter is a' is the wordplay.
'not one famous painter' becomes 'tit' (I am not sure about this - if you are sure you should believe this answer much more).
'is a' becomes 'an'.
'tit'+'an'='TITAN'
Can you help me to learn more?
(Other definitions for titan that I've seen before include "A giant; Saturn moon" , "Jupiter's largest satellite" , "immense figure" , "Taint in a great man" , "Goddess" .)