The most common and most likely answer to this crossword clue is the 8 letter word ENACTING
I've seen this crossword clue in The Daily Telegraph
E
N
A
C
T
I
N
G
More clues leading to the result ENACTING
Buddy explains!

The straight part
We know that "performing" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case performing = enacting.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 ENACTING mean?
ENACTING verb- To make (a bill) into law
- To act the part of; to play
- To do; to effect
- Enactment.