Dance band's leader has everything (4)
I believe the answer is:
ball
'dance' is the definition.
(ball is a kind of dance)
'band's leader has everything' is the wordplay.
'leader' indicates taking the first letters.
'has' means one lot of letters go next to another.
'everything' becomes 'all' (all things).
The first letter of 'bands' is 'b'.
'b'+'all'='BALL'
(Other definitions for ball that I've seen before include "Formal dance gathering" , "One spotted in competition" , "Social function for dancing" , "Sphere for sport" , "Perhaps a bouncer < 's clog" .)