Extraordinary singer's last appearance live (4)
I believe the answer is:
rare
'extraordinary' is the definition.
(I've seen this in another clue)
'singer's last appearance live' is the wordplay.
'last appearance' says to take the final letters (the letter that appears last in the word).
'live' becomes 'are' (I've seen this before).
The final letter of 'singer' is 'r'.
'r'+'are'='RARE'
(Other definitions for rare that I've seen before include "Very, very occasional" , "Not common" , "like gold dust" , "of low density" , "Rear up, being scarce" .)