Dance orchestra backing alternate pieces from usual artist (8)
I believe the answer is:
saraband
'dance' is the definition.
(I know that saraband is a type of dance)
'orchestra backing alternate pieces from usual artist' is the wordplay.
'orchestra' becomes 'band' (large musical group).
'backing' is a charade indicator (letters next to each other).
'alternate pieces from' indicates alternate letters.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
The alternating letters of 'usual' are 'sa'.
'sa'+'ra'='sara'
'band' put after 'sara' is 'SARABAND'.
(Other definitions for saraband that I've seen before include "Slow Spanish dance" , "dance music" , "Old, courtly dance" , "Stately dance" .)