Where actors appear at the start? (5)
I believe the answer is:
onset
'start?' is the definition.
(both can mean the beginning of something)
'where actors appear at the' is the wordplay.
I cannot really understand how this works, but
'at' could be 'on' (location) and 'on' is found within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'se' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for onset that I've seen before include "Beginning; violent attack" , "Storming" , "Start - attack" , "Start, beginning" , "17 down [ASSAULT]" .)