The most common and most likely answer to this crossword clue is the 8 letter word PROMOTER
I've seen this crossword clue in The Guardian
P
R
O
M
O
T
E
R
Buddy explains!

The straight part
We know that "impresario" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case impresario = promoter.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 PROMOTER mean?
PROMOTER noun- One who promotes, particularly with respect to entertainment events or goods.
- The section of DNA that controls the initiation of RNA transcription as a product of a gene.
- An accelerator of catalysis that is not itself a catalyst.