Pluck guitar in US, ground-breaking device there (4-2)

'ground-breaking device there' is the definition.
I know nothing about this answer so I cannot judge whether this works.

'pluck guitar in us' is the wordplay.
I cannot quite understand how this works, but
'pluck' could be 'pick' (synonyms) and 'pick' is located in the answer.
'guitar in us' could be 'ax' (US spelling of 'axe' - informal term for guitar) and 'ax' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...