Understand refusal to hear? (4)
I believe the answer is:
know
'understand' is the definition.
(I've seen this before)
'refusal to hear?' is the wordplay.
'refusal' becomes 'no'.
'to hear?' shows a homophone (sound like) (I've seen 'hear' mean this).
'no' sounds like 'KNOW'.
(Other definitions for know that I've seen before include "Have information" , "Be aware of (something)" , "Be sure of something" , "Recognise" , "Ken" .)