Star, a sister played lead in 'Kismet' (8)
I believe the answer is:
asterisk
'star' is the definition.
(I know that star can be written as asterisk)
'a sister played lead in kismet' is the wordplay.
'played' indicates an anagram (letters playing around).
'lead in' suggests taking the first letters.
The first letter of 'kismet' is 'k'.
'sister' is an anagram of 'steris'.
'a'+'steris'+'k'='ASTERISK'
(Other definitions for asterisk that I've seen before include "Printed star" , "Textual reference symbol" , "Star on a page" , "Footnote marker" , "Text-marking symbol" .)