In a temporary role on stage (6)
I believe the answer is:
acting
'on stage' is the definition.
(I've seen this before)
'in a temporary role' is the wordplay.
I cannot quite understand how this works, but
'in' is found in the answer.
'a' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for acting that I've seen before include "Taking on duties temporarily" , "Playing a part" , "Performing or standing in for another" , "Behaving in a certain way" , "Temporary - work as a thespian" .)