arranger

n. one who arranges, one who organizes or sets

In music, an arrangement refers either to a rewriting of a piece of existing music with additional new material or to a fleshing-out of a compositional sketch, such as a lead sheet. If a musical adaptation does not include new material, it is more accurately termed a transcription.
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Noun
1. a person who brings order and organization to an enterprise
(synonym) organizer, organiser
(hypernym) thinker
(hyponym) coordinator
(derivation) arrange, set up
2. a musician who adapts a composition for particular voices or instruments or for another style of performance
(synonym) adapter, transcriber
(hypernym) musician
(hyponym) orchestrator
(derivation) arrange, set

v. put in order, repair, arrange; fix, adjust; lay out, settle, sort; collocate, compose, construct; do, form; groom; set, tidy up

(n.)
One who arranges.