React fearfully to the cold? (6)

I believe the answer is:

shiver

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

'react' is the definition.
Although both the answer and definition are verbs in their base form, I don't see how one could define the other.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for shiver that I've seen before include "Smash; tremble" , "Momentary tremble" , "Shake (with cold, excitement etc)" , "Slightly shake" , "Shake uncontrollably" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.