Encourage sudden activity, being out of time (4)
I believe the answer is:
spur
'encourage' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for spur that I've seen before include "Sharp pointed projection" , "branch road" , "Kick out" , "slip road" , "Provoke" .)