Stubborn sleuth on edge had surgery (9)
I believe the answer is:
pigheaded
'stubborn' is the definition.
(similar in meaning)
'sleuth on edge had surgery' is the wordplay.
I cannot quite see how this works, but
'sleuth' could be 'pi' (private investigator) and 'pi' is located in the answer.
'had' could be 'd' (in contractions e.g. 'I'd', 'you'd' etc) and 'd' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for pigheaded that I've seen before include "Stubborn" , "Extremely obstinate" .)