They rise in surprise as Matilda reads aloud! (8)

I believe the answer is:

eyebrows

'they rise in surprise' is the definition.
(eyebrows might be raised when surprised)

I don't understand how the remainder of the clue works.

(Other definitions for eyebrows that I've seen before include "these may have been plucked for beauty" , "that may be surprisingly elevated" , "part of one's features" .)

I've seen this clue in The Guardian.

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