America's mischief, awfully sly, left UK bearing new grudge (12)
I believe the answer is:
skullduggery
'america's mischief' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'awfully sly left uk bearing new grudge' is the wordplay.
I cannot quite understand how this works, but
'left' could be 'l' (common abbreviation) and 'l' is found within the answer.
'bearing' could be 's' and 's' is located in the answer.
an anagram of 'grudge' is 'dugger' which is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for skullduggery that I've seen before include "Underhand behaviour (mainly US)" , "Underhand trickery" .)