Inability to hear case of defence? A fine point … (8)
I believe the answer is:
deafness
'inability to hear' is the definition.
(I've seen this before)
'case of defence? a fine point' is the wordplay.
'case of' suggests removing the centre (outsides of).
'fine' becomes 'f' (abbreviation).
'point' becomes 'ness' (I've seen this in other clues).
'defence' with its middle removed is 'de'.
'de'+'a'+'f'+'ness'='DEAFNESS'
(Other definitions for deafness that I've seen before include "Hearing problem" , "Inability to hear" , "Loss of hearing" .)