How many letters does the top answer for “composer of stille nacht heilige nacht” have?

The most common answer is gruber (6 letters).

Crossword clue: composer of stille nacht heilige nacht

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

gruber 6 letters wd-fact-v3

a soft thick wormlike larva of certain beetles and other insects

mohr 4 letters wd-fact-v3

A West African gazelle (Gazella mohr), having horns on which are eleven or twelve very prominent rings. It is one of the

author of stille nacht heilige nacht 60% similar → mohr

wrote stille nacht heilige nacht 60% similar → mohr