How many letters does the top answer for “lacking even the rudiments of courage; abjectly fearful” have?

The most common answer is craven (6 letters).

Crossword clue: lacking even the rudiments of courage; abjectly fearful

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

craven 6 letters wn-def

an abject coward

recreant 8 letters wn-def

a disloyal person who betrays or deserts his cause or religion or political party or friend etc.