Illegally seize something from Manchu, surprisingly (5)
I believe the answer is:
usurp
'illegally seize' is the definition.
(eg usurping a throne)
'something from manchu surprisingly' is the wordplay.
'something' indicates a hidden word (I've seen this in other clues).
'USURP' is hidden within 'from manchu surprisingly'.
(Other definitions for usurp that I've seen before include "Take control illegally" , "Take (power etc) illegally" , "Arrogate" , "Supplant (someone in power)" , "Seize (throne, e.g.)" .)