### Clue: Upright, slim, on the way to a better life (6,3,6)
### Answer: STRAIT AND NARROW 
 ### Explanation: Definition: the way to a better life
 STRAIT(upright;scrupulous) AND NARROW(slim;thin).
This is the original spelling of the phrase which originates from the Bible. The common "straight" instead of "strait" dates from the 17C, the former denoting "honest", which also fits "upright".