How many letters does the top answer for “a voice exercise; singing scales or runs to the same syllable” have?

The most common answer is solfege (7 letters).

Crossword clue: a voice exercise; singing scales or runs to the same syllable

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

solfege 7 letters wn-def

a voice exercise; singing scales or runs to the same syllable

solfeggio 9 letters wn-def

a voice exercise; singing scales or runs to the same syllable