Painter's sitter so fidgety (8)

I believe the answer is:

rossetti

I'm a little stuck... Click here to teach me more about this clue!

'painter's' is the definition.
(I've seen this before)

'sitter so fidgety' is the wordplay.
'sitter so' can be anagrammed to 'ROSSETTI'.
Though, I am not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for rossetti that I've seen before include "She wroteBleak Midwinter" , "Christina -, nineteenth century century English poet" , "Artist" , "English Pre-Raphaelite poet and painter, d. 1882" , "Dante Gabriel --, English poet/painter" .)

I've seen this clue in The Times.

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