Fuss about Nattier's first circular painting (5)
I believe the answer is:
tondo
'circular painting' is the definition.
(I've seen this before)
'fuss about nattier's first' is the wordplay.
'fuss' becomes 'todo' (I've seen this before).
'about' means one lot of letters goes inside another.
'first' indicates taking the first letters.
The initial letter of 'nattiers' is 'n'.
'todo' enclosing 'n' is 'TONDO'.
(Other definitions for tondo that I've seen before include "Artistic circle" , "One among artistic circles" , "Style of painting" , "round painting" , "Circular painting, relief carving" .)