Emperor an Orwellian pig (8)

I believe the answer is:

napoleon

I'm a little stuck... Click here to teach me more about this clue!

'emperor' is the definition.
(I know that Napoleon is a emperor)

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for napoleon that I've seen before include "Solo, perhaps" , "no longer tender" , "Ruler" , "dictator" , "No one, pal, matches this Little Corporal" .)

I've seen this clue in The Sun.

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