How many letters does the top answer for “a bit for enlarging the upper part of a hole” have?

The most common answer is counterbore (11 letters).

Crossword clue: a bit for enlarging the upper part of a hole

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

counterbore 11 letters wn-def

a bit for enlarging the upper part of a hole

countersink 11 letters wn-def

a bit for enlarging the upper part of a hole