What ten dancers will hold: an audience? (10)
I believe the answer is:
attendance
'an audience?' is the definition.
(thesaurus)
'what ten dancers will hold' is the wordplay.
'hold' indicates a hidden word (I've seen 'held' mean this).
'ATTENDANCE' can be found hidden inside 'what ten dancers will'.
(Other definitions for attendance that I've seen before include "Number at gathering" , "People present" , "Service" , "Act of being present" , "all that turned up" .)