Emperor turning pale? No, no! (8)
I believe the answer is:
napoleon
'emperor' is the definition.
(I know that Napoleon is a emperor)
'turning pale? no no' is the wordplay.
'turning' indicates anagramming the letters.
'pale'+'no'+'no'='palenono'
'palenono' is an anagram of 'NAPOLEON'.
(Other definitions for napoleon that I've seen before include "Extended nap" , "In France, former sovereign" , "French VIP" , "French general and emperor" , "Ruler" .)