How many letters does the top answer for “try to fix or mend” have?

The most common answer is fiddle (6 letters).

Crossword clue: try to fix or mend

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

fiddle 6 letters wn-def

bowed stringed instrument that is the highest member of the violin family; this instrument has four strings and a hollow

an unskilled person who tries to fix or mend 60% similar → fiddler