The most common and most likely answer to this crossword clue is the 4 letter word BASS
I've seen this crossword clue in The Guardian
B
A
S
S
More clues leading to the result BASS
Buddy explains!

The straight part
We know that "Voice" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case voice = bass.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 BASS mean?
BASS noun- A low spectrum of sound tones.
- A section of musical group that produces low-pitched sound, lower than the baritone and tenor.
- One who sings in the bass range.
- An instrument that plays in the bass range, in particular a double bass, bass guitar, electric bass or bass synthesiser.
- The clef sign that indicates that the pitch of the notes is below middle C; a bass clef.
- To sound in a deep tone.
- Of sound, a voice or an instrument, low in pitch or frequency.
- The perch; any of various marine and freshwater fish resembling the perch, all within the order of Perciformes.
- The fibrous inner bark of the linden or lime tree, used for making mats.
- Fibers from other plants, especially palm trees
- Anything made from such fibers, such as a hassock, basket or thick mat.