Make blunt, lessen (6)
I believe the answer is:
deaden
(Other definitions for deaden that I've seen before include "Muffle impact" , "Muffle (sound)" , "Muffle, make muted" , "Muffle, deprive of feeling" , "Make numb, deprive of feeling" .)
I believe the answer is:
deaden
(Other definitions for deaden that I've seen before include "Muffle impact" , "Muffle (sound)" , "Muffle, make muted" , "Muffle, deprive of feeling" , "Make numb, deprive of feeling" .)