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

'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'