Work out means of transport (5)
I believe the answer is:
train
This clue is a double definition.
'work out' is the first definition.
(training is a kind of working out)
'means of transport' is the second definition.
(I've seen this before)
(Other definitions for train that I've seen before include "Coach - coaches with engine" , "Teach, series (of events)" , "one thing after another" , "Series of gears; retinue" , "Work out" .)