Start on holiday (3)
I believe the answer is:
off
This clue is a double definition.
'start' is the first definition.
(as in 'from the off')
'on holiday' is the second definition.
(eg on holiday from work)
(Other definitions for off that I've seen before include "On holiday" , "Discontinued" , "Rotten" , "Away, or no longer on the menu perhaps" , "start to race" .)