Old rail traveller leaves (6)
I believe the answer is:
rocket
This clue is a double definition.
'old rail traveller' is the first definition.
(as in Stephenson's Rocket, early steam train)
'leaves' is the second definition.
(I know that Rocket is a type of leaf vegetable)
(Other definitions for rocket that I've seen before include "Structure that flies by expelling gases - or a reprimand" , "Self-propelled missile and a plant" , "Projectile; salad plant" , "It's propelled to a great height by combustion" , "Firework and salad ingredient" .)