The most common and most likely answer to this crossword clue is the 10 plus 7 letter word COLORATURA SOPRANO
I've seen this crossword clue in The Times
C
O
L
O
R
A
T
U
R
A
S
O
P
R
A
N
O
Buddy explains!
The straight part
We know that "one using voice to great effect" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one using voice to great effect = coloratura soprano.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.