The most common and most likely answer to this crossword clue is the 6 plus 4 letter word SCREEN TEST
I've seen this crossword clue in Independent
S
C
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E
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T
More clues leading to the result SCREEN TEST
- Audition centres arranged before makeshift set
- Double check to determine who should be put in the picture
- Cover international actor’s trial
- Erects set roughly to accommodate Neeson’s first filmed audition
- Studio check to televise big match
- Audition, as does satellite station, for example?
- Guard on Hampshire river in trial filming
- Enter sectafter second audition
- Broadcast international, shooting unknown player?
- Ten secrets about what actor may have to go through
Buddy explains!

The straight part
We know that "(activity) to determine who should be put in the picture" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case (activity) to determine who should be put in the picture = screen test.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.