### Clue: Second eleven maybe has reason boarding crazy form of transport (5,10)
### Answer: STEAM LOCOMOTIVE 
 ### Explanation: Definition: form of transport
 S(abbrev. for "second" in time notation) + TEAM(one which could be/maybe, an eleven/a sports team made up of 11 players) + [ MOTIVE(a reason for doing something) **placed after**(boarding) LOCO(slang for crazy/mental) ].
Whilst good for the clue's surface, "boarding" doesn't quite fit as a placement indicator.