Crossword Genius

A grotesque slur, due to cheating (10)

Ross

I believe the answer is:

adulterous

'cheating' is the definition.
(synonyms)

'a grotesque slur due to' is the wordplay.
'grotesque' indicates an anagram.
'slur'+'due'+'to'='slurdueto'
'slurdueto' is an anagram of 'dulterous'.
'a'+'dulterous'='ADULTEROUS'

(Other definitions for adulterous that I've seen before include "untrue" , "Betraying a legal partner" .)

I've seen this clue in The Times.
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