Stubborn sleuth got leader going (9)

I believe the answer is:

pigheaded

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

'sleuth got leader going' is the wordplay.
'sleuth' becomes 'pi' (private investigator).
'leader' suggests taking the first letters.
'going' becomes 'headed' (I can't justify this - if you can you should believe this answer much more).
The first letter of 'got' is 'g'.
'pi'+'g'+'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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