。
Calling her a fool doesn't even begin to cover it.
Literal
She [topic-は] fool [not-even-どころではない].
~どころではない is a strong intensifier that says 'we're not at the level of X — things are well past that.' Applied to 愚か者 ('fool'), it implies she's something even more extreme than just a fool — typically read as 'far worse than a fool.' (The same construction can also flip — denying the category outright — but the intensifying reading is more common with derogatory nouns.) The pattern is closely related to ~どころか, which adds an explicit corrected version (X どころか Y = 'far from X, in fact Y'). Without an explicit Y, ~どころではない leaves the listener to infer just how off the mark the original characterization was.