Celebrity, last in event to jump (5)
I believe the answer is:
start
'jump' is the definition.
('start' can be a synonym of 'jump')
'celebrity last in event' is the wordplay.
'celebrity' becomes 'star' (I've seen this before**).
'last in' indicates one should take the final letters.
The last letter of 'event' is 't'.
'star'+'t'='START'
'to' acts as a link.
(Other definitions for start that I've seen before include "Commence" , "get under way" , "Onset" , "open" , "Begin - opening move" .)