Crossword Genius

Most of this f-fur’s ruined! (4,6)

Ross

I believe the answer is:

four-fifths

'most' is the definition.

'of this f-fur's ruined' is the wordplay.
'f-fur' becomes 'ffur' ('fur' said with a stammer like 'fur' was).
'ruined' indicates an anagram.
'of'+'this'+'ffur'='ofthisffur'
'ofthisffur' anagrammed gives 'FOUR-FIFTHS'.

I've seen this clue in The Times.
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