Stun grenade in China made of wood ends disastrously (6)
I believe the answer is:
deafen
'stun' is the definition.
(thesaurus)
'grenade in china made of wood ends disastrously' is the wordplay.
'ends' says to take the final letters.
'disastrously' indicates an anagram (I've seen this in other clues).
The final letters of 'grenade in china made of wood' are 'enaefd'.
'enaefd' anagrammed gives 'DEAFEN'.
(Other definitions for deafen that I've seen before include "Deprive of hearing" , "Make unable to hear" , "Render hard of hearing" , "Cause to lose the power of hearing" , "Blowing a trumpet in someone's ear would do!" .)