Public holiday in sudden start (8)
I believe the answer is:
outbreak
'sudden start' is the definition.
(I've seen this before)
'public holiday' is the wordplay.
'public' becomes 'out' (out can mean released to the public).
'holiday' becomes 'break' (break can mean a holiday or time off).
'out'+'break'='OUTBREAK'
'in' is the link.
(Other definitions for outbreak that I've seen before include "Violent occurrence" , "Sudden start" , "disturbance" , "Sudden onset (of war, disease, etc)" , "Eruption of e.g. disease" .)