Examination — of the ears, do we hear? (4)
I believe the answer is:
oral
'examination' is the definition.
(I know that oral is a type of examination)
'of the ears do we hear?' is the wordplay.
'of the ears' becomes 'aural' (I've seen this before).
'do we hear?' indicates a 'sounds like' (homophone) clue.
'aural' is a homophone of 'ORAL'.
(Other definitions for oral that I've seen before include "Viva voce" , "Relating to the mouth - exam" , "Using speech rather than writing" , "Spoken rather than written" , "Of the voice" .)