Exercise that may be taken daily on way to work? (5)
I believe the answer is:
train
I believe this clue is a double definition.
'exercise' is the first definition.
(training is a kind of exercising)
'that may be taken daily on way to work?' is the second definition.
(a commuter might use the train to get to work)
(Other definitions for train that I've seen before include "Try to get fit" , "Number of eg carriages in a line" , "Body of followers, retinue" , "something along those lines?" , "Number of animals moving in a line, like camels" .)