Change name in secret (7)
I believe the answer is:
convert
'change' is the definition.
(I know that change can be written as convert)
'name in secret' is the wordplay.
'name' becomes 'Con'.
'in secret' becomes 'vert' (I can't justify this - if you can you should give a lot more credence to this answer).
'con'+'vert'='CONVERT'
Can you help me to learn more?
(Other definitions for convert that I've seen before include "new enthusiastic believer?" , "Change from one thing to another" , "Proselyte" , "succeed at Twickenham" , "Win over opponent" .)