Configuration of two digits, fraction and trig function, we hear (5,4)

I believe the answer is:

peace sign

'configuration of two digits' is the definition.
(sign made with two fingers)

'fraction and trig function we hear' is the wordplay.
'fraction' becomes 'peace' (I can't justify this - if you can you should give a lot more credence to this answer).
'and' is a charade indicator (letters next to each other).
'trig function' becomes 'sine' (I've seen this in another clue).
'we hear' indicates a 'sounds like' (homophone) clue.
'sine' is a homophone of 'sign'.
'peace'+'sign'='PEACE SIGN'

I've seen this clue in The Guardian.

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