The most common and most likely answer to this crossword clue is the 7 letter word TROUPER
I've seen this crossword clue in The Times
T
R
O
U
P
E
R
Buddy explains!
The straight part
We know that "actor" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case actor = trouper.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.
What does TROUPER mean?
TROUPER noun- A member of a theatrical company (a troupe).
- A veteran performer.
- A reliable, hard-working and unselfish performer; one who considers the troupe before themselves.