Joined up with the others in the bar (6)
I believe the answer is:
legato
'joined' is the definition.
Both the answer and definition are adjectives. Maybe you can see an association between them that I can't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for legato that I've seen before include "In music, the opposite of staccato" , "In music, in a smooth even manner" , "Don't play roughly" , "running into each other" , "Smoothly flowing (music)" .)