Fixed this person's shoe worn by Bill in America (9)
I believe the answer is:
immutable
'fixed' is the definition.
(thesaurus)
'this person's shoe worn by bill in america' is the wordplay.
'this person's' becomes 'I'm' (('I am' - 'this person' means the crossword setter).
'shoe' becomes 'mule' (I can't explain this - if you can you should give a lot more credence to this answer).
'worn by' indicates putting letters inside (outside letters are worn by those on the inside).
'bill in america' becomes 'tab' (american english for the bill at end of meal say).
'mule' placed around 'tab' is 'mutable'.
'im'+'mutable'='IMMUTABLE'
Can you help me to learn more?
(Other definitions for immutable that I've seen before include "Not able to be changed" , "Changeless" .)