Substituted, exchanged (8)
I believe the answer is:
replaced
I believe this is a double definition.
'substituted' is the first definition.
('replace' can be a synonym of 'substitute')
'exchanged' is the second definition.
(replacing is a kind of exchanging)
(Other definitions for replaced that I've seen before include "Substituted, exchanged" , "Put back in position" , "Substituted, supplanted" , "Led caper (anag.)" .)