Star’s part in disaster is key (8)
I believe the answer is:
asterisk
'star's' is the definition.
(synonyms)
'part in disaster is key' is the wordplay.
'part in' indicates the answer is hidden within the clue.
'ASTERISK' is hidden in the letters of 'disaster is key'.
(Other definitions for asterisk that I've seen before include "Star-shaped character used in printing" , "Star-shape on the page" , "Footnote marker" , "Star-like symbol as reference mark" , "Text-marking symbol" .)