Wager Ireland should accept no abomination
I believe the answer is:
bete noire
'abomination' is the definition.
(thesaurus)
'wager ireland should accept no' is the wordplay.
'wager' becomes 'bet' ('bet' can be a synonym of 'wager').
'ireland' becomes 'eire' ('Eire' can be a synonym of 'ireland').
'should accept' indicates putting letters inside.
'eire' going around 'no' is 'enoire'.
'bet'+'enoire'='BETE NOIRE'
(Other definitions for bete noire that I've seen before include "One particularly disliked" , "One's particular bugbear" , "Person or thing one particularly dislikes" , "undesirable" , "Object of aversion" .)