Charge American soldier up in Scottish island (7)
I believe the answer is:
arraign
'charge' is the definition.
(arraigning is a kind of charging)
'american soldier up in scottish island' is the wordplay.
'american soldier' becomes 'GI' (informal term for a US soldier).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'in' indicates putting letters inside.
'scottish island' becomes 'arran' (island off the coast of Scotland).
'gi' backwards is 'ig'.
'ig' going within 'arran' is 'ARRAIGN'.
(Other definitions for arraign that I've seen before include "Accuse of a wrong" , "Indict, accuse" , "Accuse publicly" , "Call before a court to answer an indictment" , "Summons" .)