Crossword Genius

Impervious to argument about half of deaths, full stop! (4)

Ross

I believe the answer is:

deaf

I'm a little stuck... Click here to teach me more about this clue!

'impervious' is the definition.
(thesaurus)

'argument about half of deaths full stop' is the wordplay.
I cannot quite understand how this works, but
'about' could be 'a' (abbreviation in Chambers) and 'a' is found in the answer.
The remaining letters 'def' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

'to' acts as a link.

Can you help me to learn more?

(Other definitions for deaf that I've seen before include "Unhearing" , "Unable to pick up" , "Receiving no sound" , "Rudely confident" , "Aurally challenged" .)

I've seen this clue in The Guardian.
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