Stubborn swine was first (9)

I believe the answer is:

pigheaded

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'stubborn' is the definition.
(similar in meaning)

'swine was first' is the wordplay.
'swine' becomes 'pig' (pig is a kind of swine).
'was first' becomes 'headed' (I can't explain this - if you can you should give a lot more credence to this answer).
'pig'+'headed'='PIGHEADED'

Can you help me to learn more?

(Other definitions for pigheaded that I've seen before include "Stubborn" , "Extremely obstinate" .)

I've seen this clue in The Daily Express.

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