Opening location for working film actors (5)
I believe the answer is:
onset
'opening' is the definition.
(I've seen this in another clue)
'location for working film actors' is the wordplay.
I cannot really see how this works, but
'location' could be 'set' (set is a kind of location) and 'set' is found within the answer.
'working' could be 'on' (on can mean working or activated) and 'on' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for onset that I've seen before include "Outbreak" , "Beginning (of disease etc)" , "First signs" , "Start, beginning" , "Initial stage; attack" .)