Start of a cheer (4)
I believe the answer is:
viva
'start of a cheer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for viva that I've seen before include "Kind of exam" , "Hail to the Spaniards" , "Oral examination" , "Do well in Italian" , "Long live! - oral exam" .)