Revue planned after orchestra's first collected works (6)
I believe the answer is:
oeuvre
'collected works' is the definition.
(I've seen this before)
'revue planned after orchestra's first' is the wordplay.
'planned' indicates anagramming the letters.
'after' is a charade indicator (letters next to each other).
'first' indicates taking the first letters.
The first letter of 'orchestras' is 'o'.
'revue' with letters rearranged gives 'euvre'.
'euvre' put after 'o' is 'OEUVRE'.
(Other definitions for oeuvre that I've seen before include "Body of artistic or literary work" , "All the works of an artist or writer, from French" , "(A composer's) works" , "All one's writings" , "All the works of a particular composer" .)