Nuts on plane carrying old emperor (8)
I believe the answer is:
napoleon
'emperor' is the definition.
(Napoleon is an example)
'nuts on plane carrying old' is the wordplay.
'nuts' indicates anagramming the letters (nuts can mean crazy).
'carrying' indicates putting letters inside.
'old' becomes 'o' (abbreviation).
'on'+'plane'='onplane'
'onplane' is an anagram of 'napolen'.
'napolen' enclosing 'o' is 'NAPOLEON'.
(Other definitions for napoleon that I've seen before include "Ex-dictator" , "Cake" , "A pig farmer was chased by" , "no longer tender" , "French general and emperor" .)