In disguise, spy entertaining unionist Conservative (9)
I believe the answer is:
hidebound
'conservative' is the definition.
(hidebound can mean conservative or traditional)
'in disguise spy entertaining unionist' is the wordplay.
'in disguise' becomes 'hide' (hide can mean to disguise or obscure. I am not sure about the 'in' bit.).
'spy' becomes 'bond' (James Bond).
'entertaining' is an insertion indicator.
'unionist' becomes 'u' (abbreviation as in Democratic Unionist Party).
'bond' placed around 'u' is 'bound'.
'hide'+'bound'='HIDEBOUND'
(Other definitions for hidebound that I've seen before include "Splash (with liquid)" , "Narrow-minded - ultra-conservative" , "Rigid" , "very conservative" , "Narrow" .)