One seen changing from Conservative to Green? (7)
I believe the answer is:
convert
'one seen changing' is the definition.
I can't tell whether this definition defines the answer.
'conservative to green?' is the wordplay.
'conservative' becomes 'con' (abbreviation for Conservative).
'to green?' becomes 'vert' (heraldic term for green).
'con'+'vert'='CONVERT'
'from' is the link.
Can you help me to learn more?
(Other definitions for convert that I've seen before include "Transform" , "succeed at Twickenham" , "Change from one thing to another" , "Win over opponent" , "Alter for new purpose" .)