The most common and most likely answer to this crossword clue is the 8 letter word THESPIAN
T
H
E
S
P
I
A
N
More clues leading to the result THESPIAN
- The second keyboard instrument — nothing less will do for performer
- Actor heading for theatre, in shape after running
- The turn inspiring a performer on stage
- Actor, one engaged in resort in the north
- One taking part pains the jockeys
- Actor, inept, has to be sacked
- No Oscar for 1993 film featuring special actor …
- Actor has second play’s opening covered by the Scotsman
- Actor with the drive to embrace Aristophanes, for a start
- Neat ship designed by arty type
Buddy explains!

The straight part
We know that "One plays a part" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one plays a part = thespian.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 THESPIAN mean?
THESPIAN noun- An actor or player.
- Of, or relating to drama and acting; dramatic, theatrical.