Caught thus, you’re taken by surprise (8)

I believe the answer is:

unawares

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

'by surprise' is the definition.
(thesaurus)

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

(Other definitions for unawares that I've seen before include "Unknowingly - by surprise" , "Be taken thus if off-guard" , "In ignorance" , "Without knowledge of the situation" , "New auras may be unexpected" .)

I've seen this clue in The Hindu.

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.