How many letters does the top answer for “relating to or producing insensibility” have?

The most common answer is anaesthetic (11 letters).

Crossword clue: relating to or producing insensibility

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

anaesthetic 11 letters wn-def

a drug that causes temporary loss of bodily sensations

anesthetic 10 letters wn-def

a drug that causes temporary loss of bodily sensations

of or relating to or producing a secretion 50% similar → secretory