Artist, constant member of The Mamas and the Papas, rounded figure (7)
I believe the answer is:
picasso
'artist' is the definition.
(Picasso is an example)
'constant member of the mamas and the papas rounded figure' is the wordplay.
I cannot really see how this works, but
'constant' could be 'pi' (mathematical constant) and 'pi' is found in the answer.
'of' could be 'o' and 'o' is found within the answer.
'figure' could be 'c' (I've seen this in other clues) and 'c' is located in the answer.
The remaining letters 'ass' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for picasso that I've seen before include "Cubist artist" , "Prominent cubist" , "20th century painter" , "pioneer of Cubism" , "Spanish painter and sculptor" .)