Accepted stage acts worked alternately (4,5)
I believe the answer is:
took turns
'worked alternately' is the definition.
The definition and answer can be both related to change as well as being past participle verbs.
Maybe you can see an association between them that I can't see?
'accepted stage acts' is the wordplay.
I cannot quite see how this works, but
'accepted' could be 'took' (take can mean to accept something) and 'took' is located in the answer.
'acts' could be 'turns' (turn is a kind of act) and 'turns' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for took turns that I've seen before include "alternated" , "rotated" .)