Rearranging cast or parts for players (6)
I believe the answer is:
actors
'for players' is the definition.
('actor' can be a synonym of 'player')
'rearranging cast or parts' is the wordplay.
'rearranging' indicates anagramming the letters (I've seen 'rearranged' mean this).
'parts' is an insertion indicator (in the sense of cuts or separates).
'cast' with letters rearranged gives 'acts'.
'acts' going around 'or' is 'ACTORS'.
(Other definitions for actors that I've seen before include "Players on stage" , "Theatrical performers" , "They 23 down" , "Thespians" , "Luvvies" .)