How many letters does the top answer for “raise in a relief” have?

The most common answer is boss (4 letters).

Crossword clue: raise in a relief

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

boss 4 letters wn-def

a person who exercises control over workers

emboss 6 letters wn-def

raise in a relief