How many letters does the top answer for “an entrenched fortification; a position protected by trenches” have?

The most common answer is entrenchment (12 letters).

Crossword clue: an entrenched fortification; a position protected by trenches

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

entrenchment 12 letters wn-def

an entrenched fortification; a position protected by trenches

intrenchment 12 letters wn-def

an entrenched fortification; a position protected by trenches