Sovereign in purse changed by me (7)
I believe the answer is:
supreme
'sovereign' is the definition.
(I know that sovereign can be written as supreme)
'purse changed by me' is the wordplay.
'changed' indicates anagramming the letters.
'by' is a charade indicator (letters next to each other).
'purse' with letters rearranged gives 'supre'.
'supre'+'me'='SUPREME'
'in' acts as a link.
(Other definitions for supreme that I've seen before include "Highest in authority; rich cream sauce (dish)" , "over the top" , "Most excellent" , "Ranked highest" , "Creamy sauce" .)