Sort of band playing alongside rising celebrity (3-3)
I believe the answer is:
one-man
'sort of band' is the definition.
(I've seen this in another clue)
'playing alongside rising celebrity' is the wordplay.
'playing' becomes 'on' (on can mean playing or performing).
'alongside' says to put letters next to each other.
'rising' says the letters should be written in reverse (in a down clue, letters go up).
'celebrity' becomes 'name' (as in a 'big name').
'name' written backwards gives 'eman'.
'on'+'eman'='ONE-MAN'
(Another definition for one-man that I've seen is " (Of show) performed by a single person".)