Fred Astaire's sister (5)
I believe the answer is:
adele
'fred astaire's sister' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for adele that I've seen before include "Performer" , "Popular female singer" , "girl" , "Singer with albums titled 19, 21 and 25" , "Female singer from London" .)