Not changing costume (7)
I believe the answer is:
uniform
This clue is a double definition.
'not changing' is the first definition.
(I've seen this before)
'costume' is the second definition.
(both can mean clothing)
(Other definitions for uniform that I've seen before include "The same throughout" , "Distinctive outfit" , "Identifying clothing" , "Distinctive clothing worn by a group" , "Even; clothing" .)