Frenchman's refusal to accept a foreigner as emperor (8)
I believe the answer is:
napoleon
'emperor' is the definition.
(I know that Napoleon is a emperor)
'frenchman's refusal to accept a foreigner' is the wordplay.
'frenchman's refusal' becomes 'non' ('no' in French).
'to accept' is an insertion indicator.
'foreigner' becomes 'pole'.
'a'+'pole'='apole'
'non' going around 'apole' is 'NAPOLEON'.
'as' acts as a link.
(Other definitions for napoleon that I've seen before include "A pig farmer was chased by" , "Emperor - brandy" , "Corporal and emperor" , "The familiar Bonaparte" , "Leading pig in Animal Farm" .)