Crossword Genius

Rebuke insane oaf with a leer that's nasty (1,4,2,4,3)


I believe the answer is:

a flea in ones ear

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'rebuke' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'insane oaf with a leer that's nasty' is the wordplay.
'with' says to put letters next to each other.
'that's nasty' is an anagram indicator.
'insaneoafaleer' anagrammed gives 'A FLEA IN ONES EAR'.

Can you help me to learn more?

(Other definitions for a flea in ones ear that I've seen before include "Tom may have found irritating -" , "one that has jumped into the canal?" , "Rocket" , "Stinging rebuff (colloq.) (1,4,2,4,3)" , "Snub" .)

I've seen this clue in The Telegraph.
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