Crossword Genius

Umpteen converts set about Catholic, small proportion (3,6)

Ross

I believe the answer is:

per centum

'proportion' is the definition.
(I know that per centum is a type of proportion)

'umpteen converts set about catholic small' is the wordplay.
'converts' indicates an anagram.
'set about' is an insertion indicator.
'catholic small' becomes 'RC' (abbreviation for Roman Catholic; 'small' suggests an abbreviation).
'umpteen' anagrammed gives 'peentum'.
'peentum' going around 'rc' is 'PER CENTUM'.

(Another definition for per centum that I've seen is " in each ton".)

I've seen this clue in The Guardian.
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