Painter's frames for rococo triptych a stunning hit (6)
I believe the answer is:
rothko
'painter's' is the definition.
(Mark Rothko, 1903-1970)
'frames for rococo triptych a stunning hit' is the wordplay.
I cannot quite see how this works, but
'stunning hit' could be 'ko' (knock out blow in boxing) and 'ko' is present in the answer.
The remaining letters 'roth' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for rothko that I've seen before include "Mark --, US abstract painter" , "Mark --, US artist" , "Sudden violent release" , "US abstract expressionist" .)