Change direction in secret (7)
I believe the answer is:
convert
'change direction in secret' is the definition.
'convert' can be an answer for 'change' (converting is a kind of changing). I'm unsure of the 'direction in secret' bit.
'change direction in secret' is the wordplay.
'change direction' becomes 'n' (I can't justify this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'secret' becomes 'covert' ('covert' can be similar in meaning to 'secret').
'n' inserted inside 'covert' is 'CONVERT'.
Can you help me to learn more?
(Other definitions for convert that I've seen before include "Change from one thing to another" , "Alter for new purpose" , "new enthusiastic believer?" , "succeed at Twickenham" , "Win over opponent" .)