Possible secret of not having to pay (4-4)
I believe the answer is:
scot-free
'not having to pay' is the definition.
(I've seen this before)
'possible secret of' is the wordplay.
'secret of' can be anagrammed to 'SCOT-FREE'.
However, I am not clear how this is indicated.
Can you help me to learn more?
(Other definitions for scot-free that I've seen before include "Unharmed, not punished like kilted gent" , "Entirely without penalty or injury" , "Without loss or penalty" , "Unharmed, not punished - like Angus at liberty?" , "Completely without penalty" .)