Accuse American soldier back in island on the Firth of Clyde (7)
I believe the answer is:
arraign
'accuse american soldier back' is the definition.
'arraign' can be an answer for 'accuse' (arraigning is a kind of accusing). I am not sure about the 'american soldier back' bit.
'island on the firth of clyde' is the wordplay.
'island' becomes 'arran' (I've seen this before).
'on' is an insertion indicator (as in clothing \'on\' a person).
'the firth of clyde' becomes 'ig' (I can't explain this - if you can you should believe this answer much more).
'arran' placed around 'ig' is 'ARRAIGN'.
'in' is the link.
Can you help me to learn more?
(Other definitions for arraign that I've seen before include "Call before a court to answer an indictment" , "Call to account" , "Accuse of a wrong" , "Indict, accuse" , "Complain about" .)