Act in accordance with and you’ll succeed (6)
I believe the answer is:
follow
'succeed' is the definition.
('follow' can be a synonym of 'succeed')
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for follow that I've seen before include "Ensue" , "Go along (a route)" , "Grasp" , "Trail" , "Pursue or understand" .)