Orderly in train catches rebellious lout (7)
I believe the answer is:
regular
'orderly' is the definition.
(similar in meaning)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for regular that I've seen before include "orderly" , "Full-time soldier" , "Soldier - uniform" , "In accordance with a fixed order" , "Even - constant" .)