Crossword puzzle clue "vessel for twosomes"

to put into an ark (a coffer)

ADAGIO, a piece of music to be played slowly

AXLE, a shaft upon which a wheel revolves

BEAST, to punish or torture (someone) in a manner that involves excessive physical exercise

COUPLE, to unite in pairs

DUAD, a pair, also DYAD

DUET, to perform a duet

DUO, two people considered a pair for a specific reason