Fortune Truss keeps after taxes (3)
I believe the answer is:
net
'after taxes' is the definition.
(I've seen this before)
'fortune truss keeps' is the wordplay.
'keeps' indicates a hidden word.
'NET' is hidden in the letters of 'fortune truss'.
(Other definitions for net that I've seen before include "Make" , "difficulty" , "Fish-catcher" , "land" , "Snare or trap" .)