Sadie's exchanging confidences (6)
I believe the answer is:
asides
'confidences' is the definition.
'sadie's exchanging' is the wordplay.
'exchanging' indicates an anagram (I've seen 'exchange' mean this).
'sadies' with letters rearranged gives 'ASIDES'.
(Other definitions for asides that I've seen before include "Daises (anag.)" , "Players aren't meant to hear these" , "confidences passed on to spectators by players" , "Incidental remarks" , "communications not intended for everyone" .)