How many letters does the top answer for “after the manner of an acrostic.” have?

The most common answer is acrostically (12 letters).

Crossword clue: after the manner of an acrostic.

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

acrostically 12 letters web-def

After the manner of an acrostic.

after the manner of a tinker. 50% similar → tinkerly

after the manner of deists. 50% similar → deistically

in a iambic manner; after the manner of iambics. 50% similar → iambically